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A Moist PBL Parameterization for Large-Scale Models and Its Application to Subtropical Cloud-Topped Marine Boundary Layers
Science Conference Proceedings (OSTI)
A new general purpose boundary layer parameterization that permits realistic treatment of stratocumulus-capped boundary layers (SCBLs) with coarse vertical resolution is described. It combines a 1.5-order turbulent closure model with an ...
Herv� Grenier; Christopher S. Bretherton
Seasonal Simulations of the Planetary Boundary Layer and Boundary-Layer Stratocumulus Clouds with a General Circulation Model
The UCLA general circulation model (GCM) has been used to simulate the seasonally varying planetary boundary layer (PBL), as well as boundary-layer stratus and stratocumulus clouds. The PBL depth is a prognostic variable of the GCM, incorporated ...
David A. Randall; James A. Abeles; Thomas G. Corsetti
The Sensitivity of the Numerical Simulation of the Southwest Monsoon Boundary Layer to the Choice of PBL Turbulence Parameterization in MM5
Summertime convection over Arizona typically begins in the early afternoon and continues into the night. This suggests that the evolution of the daytime planetary boundary layer is important to the development of Arizona convection. If numerical ...
David R. Bright; Steven L. Mullen
Dynamical Modeling of Flow in Cumulus-Filled Boundary Layers
A primitive equation planetary boundary layer (PBL) model is constructed and applied to simulate the downwind evolution of coupled dynamic, thermodynamic and cloud properties in the PBL over warmer mean. A multilayered approach is adopted to ...
Chiu-Wai Yuen
Derivation of Turbulent Kinetic Energy from a First-Order Nonlocal Planetary Boundary Layer Parameterization
Turbulent kinetic energy (TKE) is derived from a first-order planetary boundary layer (PBL) parameterization for convective boundary layers: the nonlocal K-profile Yonsei University (YSU) PBL. A parameterization for the TKE equation is developed ...
Hyeyum Hailey Shin; Song-You Hong; Yign Noh; Jimy Dudhia
Behavior of Turbulence Statistics in the Convective Boundary Layer
Velocity variances in the convective boundary layer are examined using data derived in PBL experiments over land (Minnesota) and ocean (the Coral Sea) supported by data from the Kansas study of the surface boundary layer. In the freely convective ...
B. B. Hicks
A New Second-Order Turbulence Closure Scheme for the Planetary Boundary Layer
A new turbulence formulation for the planetary boundary layer (PBL) is presented and compared with large-eddy simulations (LES) for the dry PBL. The new scheme contains a prognostic equation for the turbulent kinetic energy. Other second-order ...
K. Abdella; N. McFarlane
A Planetary Boundary Layer Height Climatology Derived from ECMWF Reanalysis Data
A planetary boundary layer (PBL) height climatology from ECMWF reanalysis data is generated and analyzed. Different methods are first compared to derive PBL heights from atmospheric temperature, pressure, and relative humidity (RH), which mostly ...
Axel von Engeln; Jo�o Teixeira
Convective Planetary Boundary Layer Interactions with the Land Surface at Diurnal Time Scales: Diagnostics and Feedbacks
The convective planetary boundary layer (PBL) integrates surface fluxes and conditions over regional and diurnal scales. As a result, the structure and evolution of the PBL contains information directly related to land surface states. To examine ...
Joseph A. Santanello Jr.; Mark A. Friedl; Michael B. Ek
Wave Exchange between the Ground Surface and a Boundary-Layer Critical Level
Gravity waves induced by two- and three-dimensional terrain features are examined theoretically in the planetary boundary layer (PBL) using a linear wave model that includes reabsorption at a critical level. The PBL structure is characterized by ...
Carmen J. Nappo; George Chimonas
A General Framework for an �Unmixed Layer� PBL Model
Mixed-layer models are computationally efficient, but they do not realistically represent the structure of the boundary layer under many conditions. Many of the deficiencies of the mixed-layer model can be attributed to the assumed flat profiles. ...
Martin J. Otte; John C. Wyngaard
The minisodar and planetary boundary layer studies
SciTech Connect
The minisodar, in addition to being smaller than conventional sodar, operates at higher frequencies, obtains usable signal returns closer to the surface, and can use smaller range gates. Because the max range is generally limited to the lower 200 m above the surface, the minisodar is not able to interrogate the entire daytime atmospheric Planetary Boundary Layer (PBL); however it can be a very useful tool for understanding the PBL. In concert with other instruments, the minisodar can add significant new insights to our understanding of the PBL. This paper gives examples of past and potential uses of minisodars in such situations.
Coulter, R.L.
Chaos and �Bursting� in the Planetary Boundary Layer
A theoretical study of the intermittent breakdowns of the planetary boundary layer (PBL) has been carried out using a one-dimensional, �flat� terrain, PBL model of the type originally developed by A.K. Blackadar. It was found that the turbulent ...
Douglas O. ReVelle
A Method for Estimating Planetary Boundary Layer Heights and Its Application over the ARM Southern Great Plains Site
A new objective method to determine the height of the planetary boundary layer (PBL) is presented here. PBL heights are computed using the statistical variance and kurtosis of dewpoint and virtual potential temperature differences measured from ...
Paul Schmid; Dev Niyogi
Evaluation of Three Planetary Boundary Layer Schemes in the WRF Model XIAO-MING HU
E-Print Network (OSTI)
of air from above the PBL. A sensitivity experiment with the ACM2 scheme confirms this diagnosis. 1 the planetary boundary layer (PBL), is important for air pollution modeling, and PBL parameterization schemesYamadaJanjic (MYJ), Yonsei University (YSU), and the asymmetric convective model, version 2 (ACM2)]. Comparison
The Parameterization Of the Planetary Boundary Layer in the UCLA General Circulation Model: Formulation and Results
A planetary boundary layer (PBL) parameterization for general circulation models (GCMs) is presented. It uses a mixed-layer approach in which the PBL is assumed to be capped by discontinuities in the mean profiles. Both clear and cloud-topped ...
Max J. Suarez; Akio Arakawa; David A. Randall
An Examination of Local versus Nonlocal Aspects of a TKE-Based Boundary Layer Scheme in Clear Convective Conditions
In this study, the ability of a turbulent kinetic energy (TKE)�based boundary layer scheme to reproduce the rapid evolution of the planetary boundary layer (PBL) observed during two clear convective days is examined together with the impact of ...
St�phane B�lair; Jocelyn Mailhot; J. Walter Strapp; J. Ian MacPherson
Predicting Regional Transpiration at Elevated Atmospheric CO2: Influence of the PBL�Vegetation Interaction
A coupled planetary boundary layer (PBL)�vegetation model is used to study the influence of the PBL�vegetation interaction and the ambient CO2 concentration on surface resistance rs and regional transpiration ?E. Vegetation is described using the ...
Cor M. J. Jacobs; Henk A. R. de Bruin
An Improved Model for the Turbulent PBL
Second-order turbulence models of the Mellor and Yamada type have been widely used to simulate the planetary boundary layer (PBL). It is, however, known that these models have several deficiencies. For example, assuming the production of the ...
Y. Cheng; V. M. Canuto; A. M. Howard
An Analytical Method to Evaluate Mixing Length Scales for the Planetary Boundary Layer
An analytical method to evaluate the Lagrangian length scales for a turbulent planetary boundary layer (PBL) under stable and convective conditions is described in this paper. The method is based on the Taylor's diffusion theory. Agreement with ...
G. A. Degrazia; O. L. L. Moraes; A. P. Oliveira
A Comparison of Shear- and Buoyancy-Driven Planetary Boundary Layer Flows
Planetary boundary layer (PBL) flows are known to exhibit fundamental differences depending on the relative combination of wind shear and buoyancy forces. These differences are not unexpected in that shear instabilities occur locally, while ...
Chin-Hoh Moeng; Peter P. Sullivan
Structure of the Planetary Boundary Layer and Implications for its Modeling
Through the innovative use of laboratory experiments, numerical simulations, and direct measurements, researchers have greatly extended our knowledge of planetary boundary layer (PBL) structure over the last 15 years. This paper reviews some ...
John C. Wyngaard
Lidar Observations of the Vertical Aerosol Flux in the Planetary Boundary Layer
The vertical aerosol transport in the planetary boundary layer (PBL) is investigated with lidars. Profiles of the vertical wind velocity are measured with a 2-?m Doppler wind lidar. Aerosol parameters are derived from observations with an aerosol ...
Ronny Engelmann; Ulla Wandinger; Albert Ansmann; Detlef M�ller; Egidijus �eromskis; Dietrich Althausen; Birgit Wehner
POTTY ET AL. Simulation of Boundary Layer Structure over the Indian Summer Monsoon Trough
POTTY ET AL. Simulation of Boundary Layer Structure over the Indian Summer Monsoon Trough during The planetary boundary layer (PBL) structure over the Indian summer monsoon trough region has been simulated using a regional numerical model during the passage of a monsoon depression along the monsoon trough
Raman, Sethu
Cell Merger Potential in Multicell Thunderstorms of Weakly Sheared Environments: Cell Separation Distance versus Planetary Boundary Layer Depth
Using high-resolution three-dimensional numerical experiments, this paper shows that the cell separation distance scales as 0.75 times the planetary boundary layer (PBL) depth for successful cell mergers between constructively interacting cells ...
James R. Stalker; Kevin R. Knupp
Simulation of Boundary Layer Structure over the Indian Summer Monsoon Trough during the Passage of a Depression
The planetary boundary layer (PBL) structure over the Indian summer monsoon trough region has been simulated using a regional numerical model during the passage of a monsoon depression along the monsoon trough. Monin�Obukhov similarity theory for ...
K. V. J. Potty; U. C. Mohanty; S. Raman
Toward a Unified Parameterization of the Boundary Layer and Moist Convection. Part I: A New Type of Mass-Flux Model
Higher-order closure (HOC) models have been proposed for parameterization of the turbulent planetary boundary layer (PBL). HOC models must include closures for higher-order moments (e.g., fourth moments in third-order closure models), for ...
Cara-Lyn Lappen; David A. Randall
Determination of Planetary Boundary Layer Height on Short Spatial and Temporal Scales: A Demonstration of the Covariance Wavelet Transform in Ground-Based Wind Profiler and Lidar Measurements
This article explores the application of the covariance wavelet transform (CWT) to lidar and, for the first time to the authors' knowledge, wind profiler data to examine the possibility of accurate and continuous planetary boundary layer (PBL) ...
Jaime C. Compton; Ruben Delgado; Timothy A. Berkoff; Raymond M. Hoff
Analysis of the planetary boundary layer with a database of large-eddy simulation experiments
Observational studies of a planetary boundary layer (PBL) are difficult. Ground-born measurements usually characterize only a small portion of the PBL immediately above the surface. Air-born measurements cannot be obtained close to the surface and therefore cannot capture any significant portion of the PBL interior. Moreover, observations are limited in choice of instrumentation, time, duration, location of measurements and occasional weather conditions. Although turbulence-resolving simulations with a large-eddy simulation (LES) code do not supplant observational studies, they provide valuable complementary information on different aspect of the PBL dynamics, which otherwise difficult to acquire. These circumstances motivated development of a medium-resolution database (DATABASE64) of turbulence-resolving simulations, which is available on ftp://ftp.nersc.no/igor/. DATABASE64 covers a range of physical parameters typical for the barotropic SBL over a homogeneous rough surface. LES runs in DATABASE64 simulate...
Esau, Igor
Simulation of a Stratocumulus-Topped Planetary Boundary Layer: Intercomparison among Different Numerical Codes
This paper reports an intercomparison study of a stratocumulus-topped planetary boundary layer (PBL) generated from ten 3D large eddy simulation (LES) codes and four 2D cloud-resolving models (CRMs). These models vary in the numerics, the ...
C-H. Moeng; W. R. Cotton; B. Stevens; C. Bretherton; H. A. Rand; A. Chlond; M. Khairoutdinov; S. Krueger; W. S. Lewellen; M. K. MacVean; J. R. M. Pasquier; A. P. Siebesma; R. I. Sykes
Evaluation of Planetary Boundary Layer Scheme Sensitivities for the Purpose of Parameter Estimation
for the parameters within the Asymmetrical Convective Model, version 2 (ACM2) planetary boundary layer (PBL) scheme of the simulations to these 10 particular ACM2 parameters within their plausible physical bounds. The most Appropriate treatment of vertical mixing is an essen- tial component of meteorological and air quality models
Parameterization of PBL Processes in an Atmospheric General Circulation Model: Description and Preliminary Assessment
This paper presents the basic features of a newly developed planetary boundary layer (PBL) parameterization, and the performance assessment of a version of the University of California, Los Angeles (UCLA), Atmospheric General Circulation Model (...
Celal S. Konor; Gabriel Cazes Boezio; Carlos R. Mechoso; Akio Arakawa
PBL Stratiform Cloud Inhomogeneities Thermally Induced by the Orography: A Parameterization for Climate Models
This paper proposes a parameterization for use in climate models of the orographic variance and associated thermal circulation's impact on the macroscopic behavior of planetary boundary layer (PBL) stratiform clouds. Orographically induced ...
Rafael Terra
Modeling the Benthic Boundary Layer
A second-order turbulence closure model is used to study the development of the benthic boundary layer. Results are presented on the effects of a time-dependent oscillatory forcing flow and an initially stably stratified density gradient. Using ...
K. J. Richards
Large-Eddy Boundary Layer Entrainment
A series of large-eddy simulations have been performed to explore boundary layer entrainment under conditions of a strongly capped inversion layer with the boundary layer dynamics driven dominantly by buoyant forcing. Different conditions ...
D. C. Lewellen; W. S. Lewellen
Impact of Flow Dependence, Column Covariance, and Forecast Model Type on Surface-Observation Assimilation for Probabilistic PBL Profile Nowcasts
A probabilistic verification and factor-separation analysis (FSA) elucidate skillful nowcasts of planetary boundary layer (PBL) temperature, moisture, and wind profiles with a single-column model (SCM) and ensemble filter (EF) assimilation of ...
Dorita Rostkier-Edelstein; Joshua P. Hacker
Monsoon Trough Boundary Layer Experiment (MONTBLEX)
The Monsoon Trough Boundary Layer Experiment (MONTBLEX) is a multi-institutional, all-India coordinated program to study the atmospheric boundary-layer processes in the monsoon trough (MT) area of northern India. The experiment is being organized ...
Malti Goel; H. N. Srivastava
Ocean Boundary Mixing during Ekman Layer Arrest
As a water parcel comes into contact with an ocean boundary, energy is dissipated within the boundary layer with some fraction directed into vertical mixing. In a stratified flow this increases the potential energy associated with the density ...
Scott A. Condie
The GATE Boundary Layer Instrumentation System (BLIS)
A tethered sonde, the Boundary Layer Instrument System (BLIS), was designed for use from shipboard platforms in the GARP Atlantic Tropical Experiment (GATE). This system was able to monitor the thermal and kinematic properties of the boundary ...
Donald P. Wylie; Chester F. Ropelewski
Using remotely sensed planetary boundary layer variables as estimates of areally averaged heat flux
Homogeneity across the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site is an issue of importance to all facets of the Atmospheric Radiation Measurements (ARM) program. The degree to which measurements at the central facility can be used to verify, improve, or develop relationships in radiative flux models that are subsequently used in Global Circulation Models (GCMs), for example, is tied directly to the representativeness of the local measurements at the central facility for the site as a whole. The relative variation of surface energy budget terms over a 350- km X 400km domain such as the SGP CART site can be extremely large. The Planetary Boundary Layer (PBL) develops as a result of energy inputs from widely varying surfaces. The lower atmosphere effectively integrates the local inputs; measurements of PBL structure can potentially be used for estimates of surface heat flux over scales on the order of tens of kilometers. This project is focusing on two PBL quantities that are intimately tied to the surface heat flux: (1) the height of the mixed layer, z, that grows during daytime due to sensible heat flux input from the surface; and (2) the convective velocity scale, normally a scaling parameter defined by the product of the sensible heat flux and z, but in this case defined by coherent structures that connect the surface layer and the capping inversion that defines z.
Coulter, R.L.; Martin, T.J.; Holdridge, D.J.
ARM - Measurement - Planetary boundary layer height
NLE Websites -- All DOE Office Websites (Extended Search)
govMeasurementsPlanetary boundary layer height govMeasurementsPlanetary boundary layer height ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Planetary boundary layer height Top of the planetary boundary layer; also known as depth or height of the mixing layer. Categories Atmospheric State Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments VCEIL : Vaisala Ceilometer External Instruments NCEPGFS : National Centers for Environment Prediction Global Forecast System Field Campaign Instruments
An Evaluation of Boundary Conditions for Modeling Urban Boundary Layers
DOE Green Energy (OSTI)
Numerical modeling of the urban boundary layer is complicated by the need to describe airflow patterns outside of the computational domain. These patterns have an impact on how successfully the simulation is able to model the turbulence associated with the urban boundary layer. This talk presents experiments with the model boundary conditions for simulations that were done to support two Department of Energy observational programs involving the Salt Lake City basin. The Chemical/Biological Non-proliferation Program (CBNP) is concerned with the effects of buildings on influencing dispersion patterns in urban environments. The Vertical Transport and Mixing Program (VTMX) investigating mixing mechanisms in the stable boundary layer and how they are influenced by the channeling caused by drainage flows or by obstacles such as building complexes. Both of these programs are investigating the turbulent mixing caused by building complexes and other urban obstacles.
Calhoun, R.J.; Chan, S.T.; Lee, R.L.
Subsidence in the Nocturnal Boundary Layer
Nights with clear skies and strong radiative cooling that favor the formation of statically stable nocturnal boundary layers (NBL) are also those nights most likely to have subsidence, because of the presence of synoptic high-pressure regions. ...
Merrilee A. Carlson; Roland B. Stull
Evaluating Formulations of Stable Boundary Layer Height
Stable boundary layer height h is determined from eddy correlation measurements of the vertical profiles of the buoyancy flux and turbulence energy from a tower over grassland in autumn, a tower over rangeland with variable snow cover during ...
D. Vickers; L. Mahrt
Development of a Two-Dimensional Finite-Element PBL Model and Two Preliminary Model Applications
We have developed a two-dimensional finite-element model for simulating atmospheric flow in the planetary boundary layer (PBL) of the earth. The finite-element method provides a useful alternative to the conventional finite-difference method in ...
L. P. Chang; E. S. Takle; R. L. Sani
Causal Viscosity in Accretion Disc Boundary Layers
The structure of the boundary layer region between the disc and a comparatively slowly rotating star is studied using a causal prescription for viscosity. The vertically integrated viscous stress relaxes towards its equilibrium value on a relaxation timescale $\\tau$, which naturally yields a finite speed of propagation for viscous information. For a standard alpha prescription with alpha in the range 0.1-0.01, and ratio of viscous speed to sound speed in the range 0.02-0.5, details in the boundary layer are strongly affected by the causality constraint. We study both steady state polytropic models and time dependent models, taking into account energy dissipation and transport. Steady state solutions are always subviscous with a variety of $\\Omega$ profiles which may exhibit near discontinuities. For alpha =0.01 and small viscous speeds, the boundary layer adjusted to a near steady state. A long wavelength oscillation generated by viscous overstability could be seen at times near the outer boundary. Being confined there, the boundary layer remained almost stationary. However, for alpha =0.1 and large viscous speeds, short wavelength disturbances were seen throughout which could significantly affect the power output in the boundary layer. This could be potentially important in producing time dependent behaviour in accreting systems such as CVs and protostars.
W. Kley; J. C. B. Papaloizou
DOE/SC-ARM/TR-132 Planetary Boundary Layer (PBL) Height Value
Laboratory S Liu University of Maryland M Fischer Lawrence Berkeley National Laboratory August 2013 Version 1.0 1 Now at the U.S. Department of Energy, Climate & Environmental...
ARM - Field Campaign - Boundary Layer Cloud IOP
govCampaignsBoundary Layer Cloud IOP govCampaignsBoundary Layer Cloud IOP Campaign Links Campaign Images Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Boundary Layer Cloud IOP 2005.07.11 - 2005.08.07 Lead Scientist : William Shaw For data sets, see below. Description Investigators from Pacific Northwest National Laboratory, in collaboration with scientists from a number of other institutions, carried out a month of intensive measurements at the ARM Climate Research Facility on the North Slope of Alaska in the summer of 2005. The purpose of these measurements was to determine how much the arctic land surface modifies the way low clouds reflect, absorb, and transmit solar and infrared radiation. This is an important problem because arctic clouds play a prominent role in
Boundary-Layer Damping of Baroclinic Instability
A shooting method is applied to a 100-level perturbation model with an explicit Ekman layer. Growth rates for a no-slip boundary condition are similar to those found previously. It is noted that the large cross-isobaric flow of the classic Ekman ...
D. O. Staley
Spectral Scaling in a Tidal Boundary Layer
The simple scaling of a tidal bottom boundary layer by the shear velocity, u*, and the wall to the wall describes well the mean Bow field. To test the full extent of this scaling measurements were made of the turbulence spectra in a natural tidal ...
Thomas F. Gross; Arthur R. M. Nowell
Dissipative Waves Excited by Gravity-Wave Encounters with the Stably Stratified Planetary Boundary Layer
We suggest that the strata of strong echo returns frequently revealed by remote-sensor records of the stably stratified planetary bound layer (PBL) represent the wavefronts of dissipative waves (viscous and thermal-conduction waves) excited by ...
William H. Hooke; R. Michael Jones
Quasi-Steady Analysis of a PBL Model with an Eddy-Diffusivity Profile and Nonlocal Fluxes
Analytic solutions to a planetary boundary layer (PBL) model with an eddy-diffusivity profile (i.e., a K profile) and nonlocal fluxes are presented for the quasi-steady regime. The solutions demonstrate how different processes contribute to the ...
Bjorn Stevens
A Cloudiness Transition in a Marine Boundary Layer
In situ aircraft data and lidar data are used to analyze a transition in the boundary layer thermodynamic structure from a clear boundary layer through small cumulus and broken stratocumulus to a deck of solid stratocumulus. The data was ...
Alan K. Betts; Reinout Boers
Single-Point Closures in a Neutrally Stratified Boundary Layer
Closure assumptions often employed in single-point closure models for boundary-layer applications are evaluated against a neutrally stratified planetary boundary-layer flow generated by large-eddy simulation. The contributions from slow and rapid ...
Anders Andr�n; Chin-Hoh Moeng
BLIPS: A System for Studying Benthic Boundary Layer Dynamics
A Boundary Layer Interaction Profiting System (BLIPS) has been developed to measure kinematic quantities necessary for verification of theoretical, two-phase boundary layer flow models. BLIPS sensors include electromagnetic current meters, ...
Charles E. Adams Jr.; Winfield Hill; Rodney Fredericks
Autumnal Mixed-Phase Cloudy Boundary Layers in the Arctic
Two mixed-phase cloudy boundary layer events observed over the Arctic ice pack in autumn are extensively analyzed. The local dynamic and thermodynamic structure of the boundary layers is determined from aircraft measurements including analysis of ...
James O. Pinto
The Role of Boundary Layer Processes in Limiting PV Homogenization
A ?-plane multilevel quasigeostrophic channel model with interactive static stability and a simplified parameterization of atmospheric boundary layer physics is used to study the role of different boundary layer processes in eddy equilibration ...
Yang Zhang; Peter H. Stone; Amy Solomon
Alternative Nonlocal Descriptions of Boundary-Layer Evolution
Two alternative parameterizations for nonlocal turbulence mixing are tested in a 1D boundary-layer model against a dataset from the 1983 Boundary-Layer Experiment (BLX83) in Oklahoma. One method, proposed previously by Stull and Driedonks, is ...
Qing Zhang; Roland Stull
Evaluation of Boundary Layer Depth Estimates at Summit Station, Greenland
Boundary layer conditions in polar regions have been shown to have a significant impact on the levels of trace gases in the lower atmosphere. The ability to properly describe boundary layer characteristics (e.g., stability, depth, and variations ...
B. Van Dam; D. Helmig; W. Neff; L. Kramer
The Boundary Layer of Tropical Cyclone Kerry (1979)
The boundary layer structure of Tropical Cyclone Kerry (1979) is investigated using composite analysis of research aircraft, surface ship, and automatic weather station observations. The boundary layer was moist, convective, and strongly ...
Peter G. Black; Greg J. Holland
Choosing a Boundary Layer Parameterization for Tropical Cyclone Modeling
The boundary layer in a tropical cyclone is in some respects unlike that elsewhere in the atmosphere. It is therefore necessary to evaluate boundary layer parameterizations for their suitability for use in tropical cyclone simulation. Previous ...
Jeffrey D. Kepert
ARM - Field Campaign - Lower Atmospheric Boundary Layer Experiment
govCampaignsLower Atmospheric Boundary Layer Experiment govCampaignsLower Atmospheric Boundary Layer Experiment Campaign Links LABLE Website Related Campaigns 2013 Lower Atmospheric Boundary Layer Experiment 2013.05.28, Turner, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Lower Atmospheric Boundary Layer Experiment 2012.09.17 - 2012.11.13 Lead Scientist : David Turner Description Boundary layer turbulence is an important process that is parameterized in most atmospheric numerical models. Turbulence redistributes energy and mass within the boundary layer. Many different characteristics can impact the character of turbulence in the boundary layer, including different surface types, horizontal wind speed and direction, and the vertical temperature structure of the atmosphere. However, there have been few studies that have
Soot profiles in boundary-layer flames
Carbon particulate volume fractions and approximate particle size distributions are measured in a free laminar combusting boundary layer for liquid hydrocarbon fuels (n-heptane, iso-octane, cyclohexane, cyclohexene, toluene) and polymethylmethacrylate (PMMA). A multiwavelength laser transmission technique determines a most probable radius and the total particle concentration, which are two parameters in an assumed form for the size distribution. In the combusting boundary layer, a sooting region exists between the pyrolyzing fuel surface and the flame zone. The liquid fuel soot volume fractions, f/sub v/, range from f/sub v/ approx. 10/sup -7/ for n-heptane, a paraffin, to f/sub v approx. 10/sup -5/ for toluene, an aromatic. The PMMA volume fractions, f/sub v/ approx. 5 X 10/sup -7/, are approximately the same as the values previously reported for pool fires. The soot volume fractions increase with height; convection of carbon particles downstream widens the soot region with height. For all fuels tested, the most probable radius is between 20 nm and 50 nm, and it changes only slightly with height and distance from the fuel surface.
Beier, R.A.; Pagni, P.J.
Numerical and Experimental Investigation of the Neutral Atmospheric Surface Layer
This study combines the experimental measurements with large-eddy simulation (LES) data of a neutral planetary boundary layer (PBL) documented by a 60-m tower instrumented with eight sonic anemometers, and a high-resolution Doppler lidar during ...
Philippe Drobinski; Pierre Carlotti; Jean-Luc Redelsperger; Valery Masson; Robert M. Banta; Rob K. Newsom
Wind and Temperature Profiles in the Radix Layer: The Bottom Fifth of the Convective Boundary Layer
In the middle of the convective atmospheric boundary layer is often a deep layer of vertically uniform wind speed (MUL), wind direction, and potential temperature (?UL). A radix layer is identified as the whole region below this uniform layer, ...
Edi Santoso; Roland Stull
Model of Trace Gas Flux in Boundary Layer
Mathematical model of the turbulent flux in the three-layer boundary system is presented. Turbulence is described as a presence of the nonzero vorticity. Generalized advection-diffusion-reaction equation is derived for arbitrary number components in the flux. The fluxes in the layers are objects for matching requirements on the boundaries between the layers.
I. I. Vasenev; I. S. Nurgaliev
A Rate Equation for the Nocturnal Boundary-Layer Height
A rate equation is derived which describes the development of the boundary-layer height under stable conditions as a function of time.
F. T. M. Nieuwstadt; H. Tennekes
Boundary Layer Flame Spread over PMMA within the Initial ...
... INTRODUCTION Boundary layer-type flames are prevalent in wall fires, ceiling fires, and wind-driven fires on flat surfaces such as floors and roofs. ...
Boundary Layer Clouds and Vegetation�Atmosphere Feedbacks
An analysis of boundary layer cumulus clouds and their impact on land surface�atmosphere exchange is presented. Seasonal trends indicate that in response to increasing insolation and sensible heat flux, both the mixed-layer height (zi) and the ...
Jeffrey M. Freedman; David R. Fitzjarrald; Kathleen E. Moore; Ricardo K. Sakai
A �Balanced� Approach to Stable Boundary Layer Dynamics
Semiempirical arguments from Roach and Nieuwstadt concerning Richardson numbers Ri, Rf in stably stratified shear layers and boundary layers appear to bypass uncertainties of turbulence closures. Here it is shown that these arguments can be ...
S. H. Derbyshire
A Theory of Gravity Wave Absorption by a Boundary Layer
A one-layer model of the atmospheric boundary layer (BL) is proposed to explain the nature of lee-wave attenuation and gravity wave absorption seen in numerical simulations. Two complex coefficients are defined: the compliance coefficient and the ...
Ronald B. Smith; Qingfang Jiang; James D. Doyle
Evolution of a Marine Boundary-Layer Jet
High-resolution profiles of temperature and wind-speed measurements were made with a tethered baloon in and above the marine boundary layer at San Nicolas Island (SNI) during a period when the cloud-free boundary layer grew from near the sea ...
H. Gerber; Simon Chang; Teddy Holt
Vertical Structure of the Tropical Boundary Layer
Obsemations presented show that the undisturbed subcloud layer near the ITCZ resembles that of the trades. Mixed and transition layers are also seen between cloud drafts during disturbed periods when shallow mixed layers (200 m) can persist for ...
Dayid R. Fitzjarrald; Michael Garstang
Dusty boundary layer in a surface-burst explosion
Dusty boundary layers are an inherent feature of explosions over ground surfaces. Detailed knowledge of dusty boundary layer characteristics is needed in explosion safety analysis (e.g., to calculate the drag loads on structures). Also, to predicct the amount of dust in the rising fireball of an explsion, one must know the dusty boundary layer swept up during the positive and negative phases of the blast wave and how much of this boundary layer dust is entrained into the stem of the dust cloud. This paper describes the results of numerical simulations of the dusty boundary layer created by a surface burst explosion. The evolution of the flow was calculated by a high-order Godunov code that solves the nonsteady conservation laws.
Kuhl, A.L. [Lawrence Livermore National Lab., El Segundo, CA (United States); Ferguson, R.E.; Chien, K.Y.; Collins, J.P. [Naval Surface Warfare Center, Silver Spring, MD (United States)
Representation of Boundary Layer Moisture Transport in Cloud-Resolving Models
One of the important roles of the PBL is to transport moisture from the surface to the cloud layer. However, how this transport process can be accounted for in cloud-resolving models (CRMs) is not sufficiently clear and has rarely been examined. A ...
Chin-Hoh Moeng; Akio Arakawa
The Layered Structure of the Winter Atmospheric Boundary Layer in the Interior of Alaska
The high-latitude winter atmospheric boundary layer of interior Alaska continually exhibits a complex layered structure as a result of extreme meteorological conditions. In this paper the occurrence of elevated inversions (EI), surface-based ...
John A. Mayfield; Gilberto J. Fochesatto
Boundary-layer updrafts driven by airflow over heated terrain
This study presents linear and nonlinear scalings for boundary-layer ascent forced by airflow over heated terrain and compares them to results from corresponding high-resolution numerical simulations. Close agreement between theory and simulation ...
Daniel J. Kirshbaum; Chun-Chih Wang
Toward Convective Boundary Layer Parameterization: A Scalar Transport Module
Recent results from large-eddy simulations indicate that the eddy diffusivity for scalar diffusion through the top of a convective boundary layer is different from that for diffusion through the bottom. From this, one can show that the eddy ...
Boundary Layer Oscillations from Thunderstorms at Sydney Airport
Analyses of wind velocity and air pressure data, acquired by a set of low-level anemometers at Sydney Airport, Australia, indicate the passage of a set of three remarkably smooth atmospheric boundary layer oscillations that traveled ahead of a ...
Richard Manasseh; Jason H. Middleton
The Surface Boundary Layer in Coastal Upwelling Regions
Observations from the Oregon, northwest Africa, Peru, and northern California shelves are used to examine the characteristics of the surface boundary layer in coastal regions during the upwelling season. The observations from these four regions ...
Steven J. Lentz
Spectral Characteristics of the Convective Boundary Layer Over Uneven Terrain
The paper describes a convective boundary layer experiment conducted in April 1978 at the Boulder Atmospheric Observatory, and examines the spectral behavior of wind velocity and temperature from the Observatory's 300 m tower, from aircraft ...
J. C. Kaimal; R. A. Eversole; D. H. Lenschow; B. B. Stankov; P. H. Kahn; J. A. Businger
Boundary Layer Characteristics over Areas of Inhomogeneous Surface Fluxes
This paper describes results from a June 1992 field program to study the response of the boundary layer over a site with well-defined extreme differences in sensible and latent heat fluxes over clearly separated areas, each with characteristic ...
J. C. Doran; W. J. Shaw; J. M. Hubbe
Analytical Parameterizations of Diffusion: The Convective Boundary Layer
A brief review is made of data bases which have been used for developing diffusion parameterizations for the convective boundary layer (CBL). A variety of parameterizations for lateral and vertical dispersion, ?y and ?z, are surveyed; some of ...
Gary A. Briggs
Nonlocal Treatment of the Buoyancy-Shear-Driven Boundary Layer
A successful description of a convective boundary layer requires that the model employed takes into account the nonlocal nature of turbulent convection. In this paper new third-order moments (TOMs) are presented and tested. Numerical solutions ...
E. Ferrero; N. Colonna
Convective Boundary Layers Driven by Nonstationary Surface Heat Fluxes
In this study the response of dry convective boundary layers to nonstationary surface heat fluxes is systematically investigated. This is relevant not only during sunset and sunrise but also, for example, when clouds modulate incoming solar ...
Robert van Driel; Harm J. J. Jonker
Composite Structure of Plumes in Stratus-topped Boundary Layers
Knowledge of convective plumes within the clear convective boundary layer (CBL) is quite advanced owing to direct measurements, tank experiments, and large-eddy simulation studies. As a result, modeling of the CBL is relatively successful. ...
Chin-Hoh Moeng; Ulrich Schumann
Measurements of Boundary Layer Profiles in an Urban Environment
Boundary layer profiles of mean temperature, velocity, and small-scale turbulence from in situ sensors, Doppler lidar, sodar, and rawinsondes are intercompared for an urban environment. A new Doppler lidar algorithm is presented to produce high-...
Rod Frehlich; Yannick Meillier; Michael L. Jensen; Ben Balsley; Robert Sharman
Benthic Boundary-Layer Velocity Profiles: Dependence on Averaging Period
The relationship between benthic boundary-layer velocity profiles and current meter averaging time is investigated using detailed (0.61 Hz) current measurements recorded within 1 m of the bottom on the inner continental shelf. The percentage of ...
Barry M. Lesht
Drizzle in Stratiform Boundary Layer Clouds. Part II: Microphysical Aspects
This is the second of two observational papers examining drizzle in stratiform boundary layer clouds. Part I details the vertical and horizontal structure of cloud and drizzle parameters, including some bulk microphysical variables. In this paper,...
R. Wood
Marine Boundary Layer Cloud Observations in the Azores
The recent deployment of the Atmospheric Radiation Measurement Program (ARM) Mobile Facility at Graciosa Island, Azores, in the context of the Clouds, Aerosol and Precipitation in the Marine Boundary Layer (CAP-MBL) field campaign added the most ...
Jasmine R�millard; Pavlos Kollias; Edward Luke; Robert Wood
Radiative Cooling Effects within and above the Nocturnal Boundary Layer
For representative tropospheric profiles of water vapor, CO2 and temperature we have calculated in situ longwave radiative flux divergence for use in a simplified second-order closure model of nocturnal boundary-layer evolution. The time ...
J. R. Garratt; R. A. Brost
Large-Eddy Simulation of the Convective Atmospheric Boundary Layer
Large-eddy simulations of a free convective atmospheric boundary layer with an overlying capping inversion are considered. Attention is given to the dependence of the results upon the various factors influencing the simulation: the subgrid model, ...
P. J. Mason
The Temporal Behavior of the Atmospheric Boundary Layer in Israel
Upper-air measurements collected for three consecutive years (1987�89) from the Israel Meteorological Service permanent sounding site, in Beit-Dagan, Israel, enabled the temporal behavior of the atmospheric boundary layer over Israel to be ...
Uri Dayan; Jacob Rodnizki
Lidar Observation of the Atmospheric Boundary Layer in Jerusalem
The temporal variation of the atmospheric boundary layer (ABL) over Jerusalem is accurately measured by means of a lidar system. The findings are explained and discussed based on the specific synoptic situation of typical summer days in the ...
Ram Hashmonay; Ariel Cohen; Uri Dayan
Evolution of Nitrogen Oxide Chemistry in the Nocturnal Boundary Layer
The nocturnal cycle of nitrogen oxides in the atmospheric boundary layer is studied by means of a one-dimensional model. The model solves the conservation equations of momentum, entropy, total water content, and of five chemical species. The ...
S. Galmarini; P. G. Duynkerke; J. Vil�-Guerau de Arellano
The Nocturnal Boundary Layer: Model Calculations Compared with Observations
The structure and evolution of the nocturnal boundary layer (NBL) is simulated using a model which includes the transfer of energy by radiation and turbulence. The radiation scheme is an accurate narrow band model which simulates the absorption ...
Stephen A. Tjemkes; Peter G. Duynkergke
Dynamics and Boundary Layer Processes in Two Asian Cyclones
An explosive and nonexplosive cyclone that developed during March 1986 along the coast of Japan are analyzed to illustrate the possible interaction of moist baroclinic dynamics, boundary layer structure and surface heat and moisture fluxes in ...
Wendell A. Nuss; Shun I. Kamikawa
Racoro Extended-Term Aircraft Observations of Boundary Layer Clouds
A first-of-a-kind, extended-term cloud aircraft campaign was conducted to obtain an in situ statistical characterization of continental boundary layer clouds needed to investigate cloud processes and refine retrieval algorithms. Coordinated by the ...
Andrew M. Vogelmann; Greg M. McFarquhar; John A. Ogren; David D. Turner; Jennifer M. Comstock; Graham Feingold; Charles N. Long; Haflidi H. Jonsson; Anthony Bucholtz; Don R. Collins; Glenn S. Diskin; Hermann Gerber; R. Paul Lawson; Roy K. Woods; Elisabeth Andrews; Hee-Jung Yang; J. Christine Chiu; Daniel Hartsock; John M. Hubbe; Chaomei Lo; Alexander Marshak; Justin W. Monroe; Sally A. McFarlane; Beat Schmid; Jason M. Tomlinson; Tami Toto
Observations of Vertical Wind Shear Heterogeneity in Convective Boundary Layers
Dual-Doppler wind syntheses from mobile radar observations obtained during the International H2O Project document some of the spatial variability of vertical wind profiles in convective boundary layers. Much of the variability of popular ...
Paul Markowski; Yvette Richardson
Sensitivity of Boundary-layer and Deep Convective Cloud Simulations...
convective clouds using a cloud resolving model (CRM). A CRM usually uses a vertical grid spacing less than 100 m to simulate boundary layer clouds such as shallow cumuli and...
Estuarine Boundary Layer Mixing Processes: Insights from Dye Experiments
A series of dye releases in the Hudson River estuary elucidated diapycnal mixing rates and temporal variability over tidal and fortnightly time scales. Dye was injected in the bottom boundary layer for each of four releases during different ...
Robert J. Chant; Wayne R. Geyer; Robert Houghton; Elias Hunter; James Lerczak
Pseudospectral Technique for Calculation of Atmospheric Boundary Layer Flows
A pseudospectral method and its numerical solution algorithm for application to boundary layer problems in the atmosphere are presented. The method introduces the evaluation of a polynomial function when the solution is expressed as the sum of a ...
H. N. Lee; J. K. Shi
Intermittent and Elliptical Inertial Oscillations in the Atmospheric Boundary Layer
As a convective boundary layer over land decays in the late afternoon, the atmosphere responds to the release of turbulent stresses. For many years, this response has been presumed to take the form of an inertial oscillation, a horizontal ...
Julie K. Lundquist
Measurements of the Marine Boundary Layer from an Airship
In 1992 and 1993, the authors made measurements of the marine boundary layer off the coast of Oregon from an airship. In 1992, these measurements consisted of coherent microwave backscatter measurements at Ku band taken from the gondola of the ...
William J. Plant; William C. Keller; Vahid Hesany; Kenneth Hayes; Karl W. Hoppel; Theodore V. Blanc
Some Turbulence Characteristics in Stable Atmospheric Boundary Layer Flow
Atmospheric boundary layer measurements during stable and near neutral condition from seven sites in different kinds of terrain have been analyzed in order to find relationships among turbulence parameters.
Ann-Sofi Smedman
A Second-Order Bulk Boundary-Layer Model
Bulk mass-flux models represent the large eddies that are primarily responsible for the turbulent fluxes in the planetary boundary layer as convective circulations, with an associated convective mass flux. In order for such models to be useful, ...
David A. Randall; Qingqiu Shao; Chin-Hoh Moeng
Daytime Evolution of Relative Humidity at the Boundary Layer Top
Data from the Hydrological and Atmospheric Pilot Experiment-Mod�lisation du Bilan Hydrigue (HAPEX-MOBILHY) field program and results from a one-dimensional model of the soil and atmospheric boundary layer are analyzed to study the daytime ...
M. Ek; L. Mahrt
Coastal Boundary Layer Characteristics during Summer Stratification in Lake Ontario
Simultaneous measurements of Eulerian and Lagrangian currents along the north shore of Lake Ontario are analyzed to provide the mean flow properties and horizontal turbulent exchange characteristics in the coastal boundary layer (CBL). The summer ...
Y. R. Rao; C. R. Murthy
Multiscale Large Eddy States in Weakly Stratified Planetary Boundary Layers
We first discuss observations of two classes of two-dimensional large eddy states in weakly stratified atmospheric boundary layers. One class is characterized by large eddies with a single horizontal scale. The other contains multiscale large ...
Pierre D. Mourad; Robert A. Brown
Dispersion of Small Suspended Particles in a Wave Boundary Layer
The dispersion of heavy suspensions in a wave boundary layer over a nonerodible bed is examined theoretically. Focusing attention on the horizontal variation of the ambient wave pattern, an effective convection-diffusion equation is derived by ...
Chiang C. Mei; Chimin Chian
Observed Diurnal Cycle Climatology of Planetary Boundary Layer Height
An observational climatology of the planetary boundary layer height (PBLH) diurnal cycle, specific to surface characteristics, is derived from 58 286 fine-resolution soundings collected in 14 major field campaigns around the world. An objective ...
Shuyan Liu; Xin-Zhong Liang
Gust Structure in the Neutral Surface Boundary Layer
Measured characteristics of gust amplitudes and times in the neutral surface boundary layer are presented. The probability of gust amplitudes exceeding a prescribed level is shown to decrease exponentially with amplitude, provided the amplitude ...
J. C. Doran; D. C. Powell
Physical Processes within the Nocturnal Stratus-topped Boundary Layer
Within the stratus-topped boundary layer many physical processes are involved: longwave radiation cooling, entrainment, latent heating, surface heating, solar heating, drizzling, etc. How all processes combine to maintain the turbulence within ...
Chin-Hoh Moeng; Shaohua Shen; David A. Randall
Convectively Driven Mixing in the Bottom Boundary Layer
Closely spaced vertical profiles through the bottom boundary layer over a sloping continental shelf during relaxation from coastal upwelling reveal structure that is consistent with convectively driven mixing. Parcels of fluid were observed ...
J. N. Moum; A. Perlin; J. M. Klymak; M. D. Levine; T. Boyd; P. M. Kosro
Boundary Layer Depth, Entrainment, and Decoupling in the Cloud-Capped Subtropical and Tropical Marine Boundary Layer
Estimates of marine boundary layer (MBL) depth and degree of decoupling for two regions of the subtropical and tropical east Pacific are presented using satellite observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the ...
Robert Wood; Christopher S. Bretherton
Time Scales of the Trade Wind Boundary Layer Adjustment
The adjustment of the trade wind atmospheric boundary layer to an abrupt sea surface warming is investigated using a large-eddy simulation (LES) and two simple bulk models: a mixed-layer model (MLM), and a model based on the mixing-line hypothesis ...
Gilles Bellon; Bjorn Stevens
PROVISIONAL AGENDA Forum on Modeling the Atmospheric Boundary Layer
turbulence, surface layer turbulence, surface heat and moisture representations, heterogenous sub-grid scale-0915 Coordinate System Roger Pielke, Sr., Chair (generalized vertical coordinate, horizontal spatial grid (on your own) 1400-1545 Sub-Grid Scale Fluxes Jon Mercurio, Chair (planetary boundary layer
A Parameter Study of Interactions Between Convective Clouds, the Convective Boundary Layer, and a Forested Surface
A numerical model was developed which included cloud parameterizations, a convective boundary layer, solar and longwave radiation, a soil layer and a parameterized forest layer. The model simulated the growth of the convective boundary layer and ...
Alfred J. Garrett
A dual mass flux framework for boundary layer convection
A dual mass flux framework for boundary layer convection A dual mass flux framework for boundary layer convection Neggers, Roel European Centre for Medium-range Weather Forecasts (ECMWF) Category: Modeling A new convective boundary layer scheme is presented that is currently being developed for the Integrated Forecasting System (IFS) of the European Centre for Medium-range Weather Forecasts (ECMWF). Part of the total turbulent flux is modeled through advective mass flux by multiple updrafts, initialized at the surface. Two groups of updrafts are explicitly represented; i) updrafts that never reach their lifting condensation level, and ii) updrafts that condensate and become cloudy. Key new ingredient is the flexibility of the associated updraft area fractions, as a function of model state. As a result, an extra degree of freedom is introduced in the
ARM - Field Campaign - Boundary Layer CO2 Using CW Lidar
govCampaignsBoundary Layer CO2 Using CW Lidar govCampaignsBoundary Layer CO2 Using CW Lidar Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Boundary Layer CO2 Using CW Lidar 2005.05.21 - 2005.05.24 Lead Scientist : Michael Dobbs Description Overflights Underway at ACRF Southern Great Plains Site (M.Dobbs/J.Liljegren) Science collaborators at ITT Industries and the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) conducted flights over the Central Facility at ACRF's Southern Great Plains (SGP) site as part of the Climate Sources and Sink (CO2) Intensive Operational Period (IOP), using a CW lidar. The objective of the flights was to validate, by demonstration and comparison with SGP ground observations, the performance of the ITT system when used in conjunction with retrieval
Properties and Parameterization of the Stable Boundary Layer over Moderate Topography
Numerical simulations are used to investigate the impact on the stable boundary layer of moderate topography (with hill heights in some cases comparable to the undisturbed boundary layer depth). Area-averaged properties of the resulting boundary ...
A. R. Brown; N. Wood
On Mixed-Layer Modeling of the Stratocumulus-Topped Marine Boundary Layer
Research aircraft measurements of a well-developed marine stratocumulus cloud-topped boundary layer, made in June 1981 off the coast of California, are analyzed using the saturation point method developed by Betts. Estimates of the cloud-top ...
Howard P. Hanson
Numerical Simulation of Boundary Layer Variables Using ??? Closure Scheme
In this study, a one-and-a-half-order ??? closure scheme is used to study the planetary boundary layer development over a full diurnal cycle using Wangara 33d-day observations as initial conditions. The simulated results are compared with a first-...
N. Ramanathan; K. Srinivasan; B. V. Seshasayee
Ceilometer Retrieval of the Boundary Layer Vertical Aerosol Extinction Structure
The CT25K ceilometer is a general-purpose cloud height sensor employing lidar technology for detection of clouds. In this paper it is shown that it can also be used to retrieve aerosol optical properties in the boundary layer. The authors present ...
K. M. Markowicz; P. J. Flatau; A. E. Kardas; J. Remiszewska; K. Stelmaszczyk; L. Woeste
Influence of Soil Moisture on Boundary Layer Cloud Development
The daytime interaction of the land surface with the atmospheric boundary layer (ABL) is studied using a coupled one-dimensional (column) land surface�ABL model. This is an extension of earlier work that focused on modeling the ABL for 31 May ...
M. B. Ek; A. A. M. Holtslag
Boundary Layer Parameterization for a Non-Gaussian Puff Model
The paper presents two boundary layer parameterizations for a model based on a general technique for solving the K equation using the truncated Gram�Charlier expansion (type A) of the concentration field and a finite set of equations for the ...
T. Tirabassi; U. Rizza
Von K�rm�n's Constant in Atmospheric Boundary Layer Flow: Reevaluated
A field experiment has been carried out with the specific objective in mind to determine the value of von K�rm�n's constant in atmospheric boundary layer flow, and also to investigate its possible dependence on the surface Rossby number Ro0. Data ...
Ulf H�gstr�m
Absorption of Internal Waves by the Benthic Boundary Layer
The interaction of near-inertial velocities with the benthic boundary layer above a flat bottom is investigated using a diagnostic model and a 3-month time series of velocity from a fixed array of current meters. The observed near-inertial ...
Eric D'Asaro
Thermally Indirect Motions in the Convective Atmospheric Boundary Layer
The energetics of the dry convective boundary layer is studied by partitioning the turbulent heat flux into thermally indirect (w???thermally direct (w???>0) components as a function of z/Zi. It is found that except for the inversion ...
J. M. Wilczak; Joost A. Businger
Effects of mesoscale surface inhomogeneities on atmospheric boundary layer transfer
Defining the nature of turbulent transfer over horizontally inhomogeneous surfaces remains one of the challenges in meteorology. Because the transfer of energy and momentum through the atmospheric boundary layer forms part of the lower boundary condition for global climate models (GCMs), the problem is important. Over the last two decades, advances in sensor and computer technology wave made good point measurements of turbulent fluxes fairly routine. A fundamental question with respect to climate models, however, is how such point measurements are related to average fluxes over the area of a GCM grid box. In this paper we will use data from the field program to depict the evolution of the boundary layer over adjacent, sharply contrasting surface types on two separate occasions. We will then use simple scaling based on the observations to argue that sub-gridscale motions would often be likely to significantly alter the estimates and resulting parameterizations of GCM-scale surface fluxes in the region.
Shaw, W.J.; Doran, J.C.; Hubbe, J.M.
Application of a Perturbation Recycling Method in the Large-Eddy Simulation of a Mesoscale Convective Internal Boundary Layer
An arrangement of boundary conditions is described and demonstrated that facilitates the large-eddy simulation (LES) of inhomogeneous boundary layers such as internal boundary layers. In addition to the domain where the internal boundary layer ...
Shane D. Mayor; Philippe R. Spalart; Gregory J. Tripoli
Influences on the Height of the Stable Boundary Layer as seen in Large-Eddy Simulations
Numerical weather prediction (NWP) models and atmospheric dispersion models rely on parameterizations of planetary boundary layer height. In the case of a stable boundary layer, errors in boundary layer height estimation can result in gross errors in boundary-layer evolution and in prediction of turbulent mixing within the boundary layer. We use large-eddy simulations (LES) of moderately stable boundary layers to characterize the effects of various physical processes on stable boundary layers. The stable boundary layer height is assumed to be a function of surface friction velocity, geostrophic wind, Monin-Obukhov length, and the strength of the temperature inversion atop the stable boundary layer. This temperature inversion induces gravity waves with a frequency determined by the strength of the temperature inversion.
Kosovic, B; Lundquist, J K
Study of atmospheric boundary layer over Hong Kong using mobile micro-pulse lidar.
??Study of the boundary layer height, also known as the mixed layer height or mixing height, is of most importance to air pollution research and� (more)
Chan, Chiu Shing (???)
Turbulent Fluxes in the Hurricane Boundary Layer. Part II: Latent Heat Flux
As part of the recent ONR-sponsored Coupled Boundary Layer Air�Sea Transfer (CBLAST) Departmental Research Initiative, an aircraft was instrumented to carry out direct turbulent flux measurements in the high wind boundary layer of a hurricane. ...
William M. Drennan; Jun A. Zhang; Jeffrey R. French; Cyril McCormick; Peter G. Black
Spatial Variability of Atmospheric Boundary Layer Structure over the Eastern Equatorial Pacific
Variations in the atmospheric boundary layer structure over the eastern equatorial Pacific are analyzed using 916 soundings collected during the First Global Atmospheric Research Program Global Experiment. Unstable boundary layer structures are ...
Bingfan Yin; Bruce A. Albrecht
The Structure of Turbulence in the Near-neutral Atmospheric Boundary Layer
In this paper, the idea of local similarity, previously used to study turbulence in the stably stratified boundary layer, is used to investigate the structure of turbulence in the neutral atmospheric boundary layer and to relate this structure to ...
A. L. M. Grant
Modeling the Effects of the Spatially Varying Sea Surface Temperature on the Marine Atmospheric Boundary Layer
A two-dimensional marine planetary boundary layer model is developed and applied to simulate the evolution of coupled dynamic, thermodynamic and cloud properties of the marine boundary layer over a zonally varying sea surface temperature field. ...
Mickey Man-Kui Wai
Boundary-Layer Transition across a Stratocumulus Cloud Edge in a Coastal Zone
We examine the lateral transition from a stratocumulus-covered boundary layer to a clear-sky convective boundary layer during onshore flow in a coastal environment, using both mobile sodar observations and a numerical model. During four ...
C. E. Skupniewicz; J. W. Glendening; R. F. Kamada
Boundary Layer under Near-Inertial Internal Waves over a Critically Sloping Bottom
Internal waves reflecting off sloping bottoms have been shown to have boundary-layer scales proportional to ?� (? is viscosity). As the characteristic slope of the wave approaches the slope of the bottom, the boundary-layer scale increases ...
R. Lee Gordon
A Case Study of the Morning Evolution of the Convective Boundary Layer Depth
Because of the importance of the convective boundary layer depth (CBLD) in determining pollutant concentrations near the surface, a study of the morning evolution of the convective boundary layer was carried out at the Central Nuclear de Almaraz, ...
Jos� A. Garc; Mar L. Cancillo; Jos� L. Cano
Large-Eddy Simulation of a Stratus-Topped Boundary Layer. Part I: Structure and Budgets
The structure of a stratus-topped boundary layer is observed through large-eddy simulation which includes the interaction of longwave radiation and turbulence processes. This simulated boundary layer has a relatively warm and dry overlying ...
Chin-Hoh Moeng
Use of Synthetic Data to Test Flight Patterns for a Boundary Layer Field Experiment
A virtual research aircraft was flown through a synthetic atmospheric boundary layer to help design a real flight plan that would allow robust turbulence statistics to be obtained in a heterogeneous, evolving, convective boundary layer. The ...
Turbulence Structure of the Hurricane Boundary Layer between the Outer Rainbands
As part of the Coupled Boundary Layers Air�Sea Transfer (CBLAST)-Hurricane program, flights were conducted to directly measure turbulent fluxes and turbulence properties in the high-wind boundary layer of hurricanes between the outer rainbands. ...
Jun A. Zhang; William M. Drennan; Peter G. Black; Jeffrey R. French
Observed Boundary Layer Wind Structure and Balance in the Hurricane Core. Part I: Hurricane Georges
The GPS dropsonde allows observations at unprecedentedly high horizontal and vertical resolution, and of very high accuracy, within the tropical cyclone boundary layer. These data are used to document the boundary layer wind field of the core of ...
Convective Boundary Layer Height Measurement with Wind Profilers and Comparison to Cloud Base
The depth of the atmospheric boundary layer is of interest in several different areas, such as chemistry, pollutant studies, and global modeling. In this research the authors describe and compare several different measurements of boundary layer ...
Alison W. Grimsdell; Wayne M. Angevine
A Method for Coupling a Parameterization of the Planetary Boundary Layer with a Hydrologic Model
Deardorff's parameterization of the planetary boundary layer is adapted to drive a hydrologic model. The method converts the atmospheric conditions measured at the anemometer height at one site to the mean values in the planetary boundary layer ...
J. D. Lin; Shu Fen Sun
Simulation of Atmospheric Boundary Layer Processes Using Local- and Nonlocal-Closure Schemes
A soil�vegetation�atmospheric boundary layer model was developed to study the performance of two local-closure and two nonlocal-closure boundary layer mixing schemes for use in meteorological and air quality simulation models. Full interaction ...
Kiran Alapaty; Jonathan E. Pleim; Sethu Raman; Devdutta S. Niyogi; Daewon W. Byun
Comparisons between Model Forecast and Observed Boundary Layer Profiles and Related Comments on Cloud Prediction
In this study comparisons are made between Met Office mesoscale model boundary layer profiles, and radiosonde data collected in the central United Kingdom during three intensive boundary layer cloud experiments. Significant differences between ...
J. D. Price; M. R. Bush
Mesoscale Boundary Layer Evolution over Complex Terrain. Part I. Numerical Simulation of the Diurnal Cycle
The continuous development of a meso-?-scale boundary layer over sloping terrain upwind of a high mountain barrier was simulated through a complete diurnal cycle using a nonhydrostatic boundary-layer model. The simulation detailed the evolution ...
David C. Bader; Thomas B. McKee; Gregory J. Tripoli
Aircraft Observations of Boundary Layer Rolls off the Coast of California
Large-scale horizontal rolls can have a significant influence on turbulent transport across the atmospheric boundary layer. The formation and maintenance of such rolls is dependent on the thermal and dynamic stability of the boundary layer (BL). ...
Ian M. Brooks; David P. Rogers
An Equatorial Diffusive Boundary Layer and the Equatorial Stacked Jets in Thermally Driven OGCMs
New equatorial boundary layer solutions are found in a reduced-gravity model with large horizontal diffusivity. Analytical and semianalytical solutions are obtained and the structure of the boundary layer is discussed. The equatorial �stacked ...
Ryo Furue
Conserved Variable Analysis of the Convective Boundary Layer Thermodynamic Structure over the Tropical Oceans
An analysis of FGGE dropwindsonde data using conserved thermodynamic variables shows mixing line structures for the convective boundary layer over the equatorial Pacific. Deeper boundary layers show a double structure. Reversals of the gradients ...
Alan K. Betts; Bruce A. Albrecht
A technique using the wavelet transform to identify and isolate coherent structures in the planetary boundary layer
A dominant feature of the convective planetary boundary layer (PBL) is the presence of coherent structures often referred to as thermal plumes. These are regions of buoyant, rising air whose maximum height is limited by the capping inversion at the top of the mixed layer. They range in diameter from 0.05 to 5 km or more, scale with the height of the mixed layer (z{sub i}), are the large-scale source of energy input to the turbulence spectrum, and provide the mechanism for transferring energy from the surface through the mixed layer and into the capping inversion. When conditions are appropriate, fair-weather cumulus clouds develop at the tops of the thermal plumes. In this sense, small cumulus clouds provide a visual description of the size, location, and lifetime of mature, active thermal plumes in a deep mixed layer. Plume development is not limited to plumes associated with cumulus clouds. Although the horizontal pattern of thermals is often apparently randomly oriented, Ferrare et al. showed that thermals can be organized into {open_quotes}thermal streets,{close_quotes} similar to cloud streets, but without clouds. The authors also used scanning lidar data to show that the horizontal cross section of thermals is roughly elliptical, with the major axis along the direction of the wind shear vector. Traveling with the mean wind, thermal plumes act as a conduit for heat and moisture between the surface and the lower troposphere. Thermal plumes can be defined either by patterns of rising air or as organized regions of enhanced {open_quotes}thermal turbulence{close_quotes} that can be depicted by large values of the temperature structure parameter, C{sub T}{sup 2} which can be evaluated with remote sensing instruments such as radar profilers and sodars. This more general description includes some regions of downward moving air and entrainment into the plume.
Coulter, R.L. [Argonne National Lab., IL (United States); Li, B.L. [Texas A& M Univ., College Station, TX (United States). Dept. of Industrial Engineering
Estimates of Surface Heat Flux from Sodar and Laser Scintillation Measurements in the Unstable Boundary Layer
Measurements of acoustic backscatter in the lower planetary boundary layer and optical line-of-sight scintillation in the surface layer are each used to compute sensible heat fluxes in the unstable surface layer. Comparisons with simultaneous low-...
R. L. Coulter; M. L. Wesely
Study of Radiative and Turbulent Processes in the Stable Boundary Layer under Weak Wind Conditions
The role of radiation and turbulence was studied in a weak wind nocturnal inversion layer using a one-dimensional model. In contrast to a strong wind stable boundary layer where cooling within the surface inversion layer is dominated by ...
S. G. Gopalakrishnan; Maithili Sharan; R. T. McNider; M. P. Singh
Low Cost Geothermal Separators BLISS Boundary Layer Inline Separator Scrubber
A new compact, low cost, and high performance separator is being developed to help reduce the installed and O and M cost of geothermal power generation. This device has been given the acronym ''BLISS'' that stands for ''Boundary Layer Inline Separator Scrubber''. The device is the first of a series of separators, and in the case of injectates, scrubbers to address the cost-reduction needs of the industry. The BLISS is a multi-positional centrifugal separator primarily designed to be simply installed between pipe supports, in a horizontal position. This lower profile reduces the height safety concern for workers, and significantly reduces the total installation cost. The vessel can demand as little as one-quarter (25%) the amount of steel traditionally required to fabricate many large vertical separators. The compact nature and high separating efficiency of this device are directly attributable to a high centrifugal force coupled with boundary layer control. The pseudo isokinetic flow design imparts a self-cleaning and scale resistant feature. This polishing separator is designed to remove moderate amounts of liquid and entrained solids.
Jung, Douglas; Wai, King
Boundary layer structure over areas of heterogeneous heat fluxes
In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations within the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moveover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discuses some initial findings from those campaigns.
Doran, J.C. (Pacific Northwest Lab., Richland, WA (United States)); Barnes, F.J. (Los Alamos National Lab., NM (United States)); Coulter, R.L. (Argonne National Lab., IL (United States)); Crawford, T.L. (National Oceanic and Atmospheric Administration, Oak Ridge, TN (United States). Air Resources Lab. Atmospheric Turbulence and Diffusion Div.)
In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moreover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations? To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discusses some initial findings from those campaigns.
Doran, J.C. [Pacific Northwest Lab., Richland, WA (United States); Barnes, F.J. [Los Alamos National Lab., NM (United States); Coulter, R.L. [Argonne National Lab., IL (United States); Crawford, T.L. [National Oceanic and Atmospheric Administration, Oak Ridge, TN (United States). Air Resources Lab. Atmospheric Turbulence and Diffusion Div.
In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations within the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moveover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations? To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discuses some initial findings from those campaigns.
In general circulation models (GCMs), some properties of a grid element are necessarily considered homogeneous. That is, for each grid volume there is associated a particular combination of boundary layer depth, vertical profiles of wind and temperature, surface fluxes of sensible and latent heat, etc. In reality, all of these quantities may exhibit significant spatial variations the grid area, and the larger the area the greater the likely variations. In balancing the benefits of higher resolution against increased computational time and expense, it is useful to consider what the consequences of such subgrid-scale variability may be. Moreover, in interpreting the results of a simulation, one must be able to define an appropriate average value over a grid. There are two aspects of this latter problem: (1) in observations, how does one take a set of discrete or volume-averaged measurements and relate these to properties of the entire domain, and (2) in computations, how can subgrid-scale features be accounted for in the model parameterizations To address these and related issues, two field campaigns were carried out near Boardman, Oregon, in June 1991 and 1992. These campaigns were designed to measure the surface fluxes of latent and sensible heat over adjacent areas with strongly contrasting surface types and to measure the response of the boundary layer to those fluxes. This paper discusses some initial findings from those campaigns.
A Two-Layer First-Order Closure Model for the Study of the Baroclinic Atmospheric Boundary Layer
A steady-state two-layer model has been developed for the baroclinic boundary layer. The lower layer is the constant flux surface layer (SL) in which the eddy viscosity K varies with height and stability according to the Monin-Obukhov similarity ...
K. Krishna
Large eddy simultations of the atmospheric boundary layer east of the Colorado Rockies
Large eddy simulation, LES, has often been carried out for the idealized situation of a simple convective boundary layer. Studies of dual Doppler radar and aircraft data from the Phoenix II experiment indicate that the boundary layer of the Colorado High Plains is not a purely convective boundary layer and it is influenced by the mountains to the west. The purpose of this study is to investigate the atmospheric boundary layer on one particular day on the Colorado High Plains. This research applies a LES nested within larger grids, which contain realistic topography and can simulate the larger-scale circulations initiated by the presence of the mountain barrier. How and to what extent the atmospheric boundary layer of the Colorado High Plains is influenced by larger scale circulations and other phenomena associated with the mountain barrier to the west is investigated. The nested grid LES reproduces the characteristics of the atmosphere for the case study day reasonably well. The mountains influence the atmospheric boundary layer over the plains to the east in several ways. The mountains contribute to the vertical shear of the horizontal winds through the thermally-induced mountain-plains circulation. As a consequence of the wind shear, the boundary layer that develops over the mountains is advected eastward over the top of the plains boundary layer, which is developing separately. This layer is marked by a mixture of gravity waves and turbulence and is atypical of a purely convective boundary layer. Just below this layer, the capping inversion of the plains boundary layer is weak and poorly defined compared to the inversions capping purely convective boundary layers. Gravity waves, triggered by the obstacle of the Rocky Mountains and by convection in the mountain boundary layer, also influence the atmosphere above the Colorado High Plains. These influences are found to have significant effects on the turbulence statistics and the energy spectra.
Costigan, K.R.; Cotton, W.R.
1396 JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY VOLUME 46 A Combined Local and Nonlocal Closure Model for the Atmospheric Boundary Layer. Part II: Application and Evaluation in a Mesoscale Meteorological Model
A new combined local and nonlocal closure atmospheric boundary layer model called the Asymmetric Convective Model, version 2, (ACM2) was described and tested in one-dimensional form and was compared with large-eddy simulations and field data in Part I. Herein, the incorporation of the ACM2 into the fifth-generation Pennsylvania State University�NCAR Mesoscale Model (MM5) is described. Model simulations using the MM5 with the ACM2 are made for the summer of 2004 and evaluated through comparison with surface meteorological measurements, rawinsonde profile measurements, and observed planetary boundary layer (PBL) heights derived from radar wind profilers. Overall model performance is as good as or better than similar MM5 evaluation studies. The MM5 simulations with the ACM2 compare particularly well to PBL heights derived from radar wind profilers during the afternoon hours. The ACM2 is designed to simulate the vertical mixing of any modeled quantity realistically for both meteorological models and air quality models. The next step, to be described in a subsequent article, is to incorporate the ACM2 into the Community Multiscale Air Quality (CMAQ) model for testing and evaluation. 1.
Jonathan E. Pleim
Ekman Pumping for Stratified Planetary Boundary Layers Adjacent to a Free Surface or Topography
In this paper, the classic Ekman pumping formulas for the vertical flow out of a boundary layer are generalized for both the layer above a rigid surface of variable slope and also for the boundary layer underneath a moving free surface. The ...
Benkui Tan
Formation and Development of Nocturnal Boundary Layer Clouds over the Southern Great Plains
The formation and evolution of nocturnal boundary layer clouds over land are studied using a simple well-mixed boundary layer theory. By analyzing the deepening rate of the mixed layer depth based on the turbulent kinetic energy budget of the ...
Ping Zhu; Bruce Albrecht; Jon Gottschalck
Long-Term Observations of the Dynamics of the Continental Planetary Boundary Layer
Time series of mixed layer depth, zi, and stable boundary layer height from March through October of 1998 are derived from a 915-MHz boundary layer profiling radar and CO2 mixing ratio measured from a 447-m tower in northern Wisconsin. Mixed ...
Chuixiang Yi; Kenneth J. Davis; Bradford W. Berger; Peter S. Bakwin
Boundary layer eddies at the Goodnoe Hills site
Data from nine instrumented meteorological towers at the MOD-2 wind turbine site at Goodnoe Hills in Washington State were analyzed to evaluate high-frequency perturbations, which were observed in the lower boundary-layer flow. Horizontal winds and temperature measurements for a period of 8 min, undisturbed by turbine operation, were available for this study. The data are in 1-s values from June 27, 1985. Throughout the study, departures from the mean for the period and for each sensor were used on area maps and on line-time and tower-time cross sections. Conventional streamline and isotach analyses were employed; they show highly organized flow fields with embedded perturbations traversing the site. Most of the flow fields have a well-developed vortical structure that reaches from the surface through the top level of the highest tower. These structures consist of a system of clockwise and counter-clockwise circulations. The wave length is about 500 to 600 m. Their wave speed is slightly greater than the mean wind speed and their movement is in the general direction of the mean flow. The results of the study show two main reasons why wind conditions and turbine power output in a wind farm may vary in a remarkable and abrupt fashion in space and time under certain circumstances: (1) The boundary-layer flow contains highly organized coherent perturbations with a typical size of 300 {times} 300 M{sup 2}. (2) The transition zones between the perturbations moving through a wind farm are associated with very definitive changes in the wind field that are on the order of meters and seconds. 2 refs., 11 figs.
Aspliden, C.I.; Wendell, L.L.; Clem, K.S.; Gower, G.L.
A Fractal Interfacial Entrainment Model for Dry Convective Boundary Layers. Part I: Model Description
An entrainment model for the convective planetary boundary layer is presented. It is based upon an ensemble-averaged view of the local entrainment interface that caps the convective mixed layer. Fractal and variational methods are used to ...
Ray F. Kamada
Moisture Transport, Lower-Tropospheric Stability, and Decoupling of Cloud-Topped Boundary Layers
Decoupling during the �Lagrangian� evolution of a cloud-topped boundary layer advected equatorward by the trade winds in an idealized eastern subtropical ocean is studied using a mixed-layer model (MLM). The sea surface temperature is gradually ...
Christopher S. Bretherton; Matthew C. Wyant
A Model for a Shear-Free Convective Boundary Layer with Parameterized Capping Inversion Structure
The paper extends Deardorff's general structure parameterization for a shear-free convective boundary layer. The model suggested employs the mixed layer hypothesis that the buoyancy (which is defined as b = g(?0 ? &rho)/?0, where ? is the density,...
E. E. Fedorovich; D. V. Mironov
Similarity Equations for Wind and Temperature Profiles in the Radix Layer, at the Bottom of the Convective Boundary Layer
In the middle of the convective boundary layer, also known as the mixed layer, is a relatively thick region where wind speed and potential temperature are nearly uniform with height. Below this uniform layer (UL), wind speed decreases to zero at ...
A New Parameterization for Shallow Cumulus Convection and Its Application to Marine Subtropical Cloud-Topped Boundary Layers. Part II: Regional Simulations of Marine Boundary Layer Clouds
The impact of physical parameterizations on simulations of cloud-topped marine boundary layers is investigated using the fifth-generation Pennsylvania State University�NCAR Mesoscale Model (MM5). Three-month MM5 simulations of the northeast and ...
James R. McCaa; Christopher S. Bretherton
Numerical simulation of the shock wave / boundary layer interaction in a shock tube by
Numerical simulation of the shock wave / boundary layer interaction in a shock tube by using a high in a shock tube after the shock wave has reflected at the end wall. When the fluid is viscous, a complex unsteady interaction takes place between the reflected shock wave and the incident boundary layer
A Boundary-Layer Model for Mars: Comparison with Viking Lander and Entry Data
A one-dimensional boundary-layer model for Mars is described, and its results are compared with Viking data. The model equations are similar to Earth boundary-layer models in that they include contributions from Coriolis, pressure gradient, and ...
Robert M. Haberle; Howard C. Houben; Rolf Hertenstein; Tomas Herdtle
Shock-unsteadiness model applied to oblique shock wave/turbulent boundary-layer interaction
Reynolds-averaged Navier-Stokes prediction of shock wave/turbulent boundary layer interactions can yield significant error in terms of the size of the separation bubble. In many applications, this can alter the shock structure and the resulting surface ... Keywords: high-speed flows, separation bubble, shock-unsteadiness, turbulence modelling, turbulent boundary layer
Amjad Ali Pasha; Krishnendu Sinha
Turbulent Fluxes in the Hurricane Boundary Layer. Part I: Momentum Flux
An important outcome from the ONR-sponsored Coupled Boundary Layer Air�Sea Transfer (CBLAST) Hurricane Program is the first-ever direct measurements of momentum flux from within hurricane boundary layers. In 2003, a specially instrumented NOAA P3 ...
Jeffrey R. French; William M. Drennan; Jun A. Zhang; Peter G. Black
Boundary Layer and Mesoscale Structure over Lake Michigan during a Wintertime Cold Air Outbreak
An investigation of a cloud-topped boundary layer during a wintertime cold air outbreak over Lake Michigan has been conducted based on research aircraft 1 and 20 Hz data for five vertically-stacked levels within the boundary layer. Mean east-west ...
Ernest M. Agee; Mary L. Hart
Boundary Layer Structure and Dynamics in Outer Hurricane Rainbands. Part II: Downdraft Modification and Mixed Layer Recovery
Recent aircraft boundary layer measurements in the vicinity of principal hurricane rainbands have confirmed that convective downdrafts are capable of transporting cool, dry, low equivalent potential temperature (?E) air to the surface, where the ...
Mark D. Powell
Crop Wind Energy Experiment (CWEX): Observations of Surface-Layer, Boundary Layer, and Mesoscale Interactions with a Wind Farm
Perturbations of mean and turbulent wind characteristics by large wind turbines modify fluxes between the vegetated surface and the lower boundary layer. While simulations have suggested that wind farms could significantly change surface fluxes of heat, ...
Daniel A. Rajewski; Eugene S. Takle; Julie K. Lundquist; Steven Oncley; John H. Prueger; Thomas W. Horst; Michael E. Rhodes; Richard Pfeiffer; Jerry L. Hatfield; Kristopher K. Spoth; Russell K. Doorenbos
Parameterization of Joint Frequency Distributions of Potential Temperature and Water Vapor Mixing Ratio in the Daytime Convective Boundary Layer
Joint frequency distributions (JFDs) of potential temperature (?) versus water vapor mixing ratio (r) within the convective boundary layer were measured during a new field experiment named Boundary Layer Experiment 1996 (BLX96). These JFDs were ...
Larry K. Berg; Roland B. Stull
Baroclinic Adjustment in an Atmosphere�Ocean Thermally Coupled Model: The Role of the Boundary Layer Processes
Baroclinic eddy equilibration and the roles of different boundary layer processes in limiting the baroclinic adjustment are studied using an atmosphere�ocean thermally coupled model. Boundary layer processes not only affect the dynamical ...
Yang Zhang; Peter H. Stone
PDF Parameterization of Boundary Layer Clouds in Models with Horizontal Grid Spacings from 2 to 16 km
Many present-day numerical weather prediction (NWP) models are run at resolutions that permit deep convection. In these models, however, the boundary layer turbulence and boundary layer cloud features are still grossly underresolved. ...
Vincent E. Larson; David P. Schanen; Minghuai Wang; Mikhail Ovchinnikov; Steven Ghan
A Climatological Study of Internal Gravity Waves in the Atmospheric Boundary Layer Overlying the Brunt Ice Shelf, Antarctica
Internal gravity waves are frequently observed in stably stratified regions of the atmospheric boundary layer. In order to determine the statistical influence of such waves on the dynamics of the boundary layer it is necessary to compile ...
J. M. Rees; J. C. W. Denholm-Price; J. C. King; P. S. Anderson
Boundary Layer Dynamics and Cross-Equatorial Hadley Circulation
The behavior of the Hadley circulation is analyzed in the context of an idealized axisymmetric atmosphere. It is argued that the cross-equatorial Hadley circulation exhibits two different regimes depending on the depth of the planetary boundary ...
Olivier Pauluis
Observations of Flow and Turbulence in the Nocturnal Boundary Layer over a Slope
Measurements were conducted on an eastern slope of the Salt Lake Basin (SLB) as a part of the Vertical Transport and Mixing Experiment (VTMX) conducted in October 2000. Of interest was the nocturnal boundary layer on a slope (in particular, ...
P. Monti; H. J. S. Fernando; M. Princevac; W. C. Chan; T. A. Kowalewski; E. R. Pardyjak
An Investigation of the Development of Cumulonimbus Systems over South Florida. Part I: Boundary Layer Interactions
This paper investigates the interactions between two developing cumulonimbus systems and the boundary layer (surface winds, pressure, divergence and temperature fields) on a case study day, 25 August 1975. These two systems formed within 45 min ...
John B. Cunning; Mark Demaria
Local Structure of the Convective Boundary Layer from a Volume-Imaging Radar
The local structure and evolution of the convective boundary layer (CBL) are studied through measurements obtained with a volume-imaging radar, the turbulent eddy profiler (TEP). TEP has the unique ability to image the temporal and spatial ...
Brian D. Pollard; Samir Khanna; Stephen J. Frasier; John C. Wyngaard; Dennis W. Thomson; Robert E. McIntosh
Numerical Prediction of Submesoscale Flow in the Nocturnal Stable Boundary Layer over Complex Terrain
Numerical weather prediction models often perform poorly for weakly forced, highly variable winds in nocturnal stable boundary layers (SBLs). When used as input to air-quality and dispersion models, these wind errors can lead to large errors in ...
Nelson L. Seaman; Brian J. Gaudet; David R. Stauffer; Larry Mahrt; Scott J. Richardson; Jeffrey R. Zielonka; John C. Wyngaard
Numerical Modeling of the Propagation Environment in the Atmospheric Boundary Layer over the Persian Gulf
Strong vertical gradients at the top of the atmospheric boundary layer affect the propagation of electromagnetic waves and can produce radar ducts. A three-dimensional, time-dependent, nonhydrostatic numerical model was used to simulate the ...
B. W. Atkinson; J-G. Li; R. S. Plant
Control of Chemical Reactions by Convective Turbulence in the Boundary Layer
The influence of convective turbulence on chemical reactions in the atmospheric boundary layer is studied by means of direct numerical simulation (DNS). An archetype of turbulent reacting flows is used to study the reaction zones and to obtain a ...
M. Jeroen Molemaker; Jordi Vil�-Guerau de Arellano
Large Eddy Simulation of Internal Boundary Layers Created by a Change in Surface Roughness
Turbulence in a ?-mesoscale internal boundary layer (IBL) formed by a discontinuous change in surface roughness has been investigated using a large eddy simulation (LES) model to explicitly treat turbulent transport. Two cases are examined: a ...
John W. Glendening; Ching-Long Lin
A Rate Equation for the Inversion Height in a Nocturnal Boundary Layer
The application of a self-similar profile in the integration of the temperature equation across the stable boundary layer leads to a rate equation for the inversion height. An analytic solution of the resulting equation is derived. Its behavior ...
F. T. M. Nieuwstadt
Sensitivity of MM5-Simulated Boundary Layer Characteristics to Turbulence Parameterizations
The sensitivity of high-resolution mesoscale simulations to boundary layer turbulence parameterizations is investigated using the fifth-generation Pennsylvania State University�NCAR Mesoscale Model (MM5) and observations from two field campaigns. ...
Larry K. Berg; Shiyuan Zhong
The Role of Longwave Radiation and Boundary Layer Thermodynamics in Forcing Tropical Surface Winds
This paper reveals major deficiencies of the existing intermediate climate models for tropical surface winds and elaborates the important roles of cloud-longwave radiational forcing and boundary layer thermodynamics in driving the tropical ...
Xiouhua Fu; Bin Wang
On the Time Scale of Nocturnal Boundary Layer Cooling in Valleys and Basins and over Plains
Sequences of vertical temperature soundings over flat plains and in a variety of valleys and basins of different sizes and shapes were used to determine cooling-time-scale characteristics in the nocturnal stable boundary layer under clear, ...
Stephan F. J. De Wekker; C. David Whiteman
Characteristics of Vertical Velocity Fluctuations in a Convective Urban Boundary Layer
Vertical air motions within the convective boundary layer over Toronto, Canada, have been observed using a monostatic Doppler echosonde. Data were acquired on cloudless days with strong insolation and light winds, when turbulence dynamics were ...
Humfrey Melling; Roland List
Simulating the Transition from Drizzling Marine Stratocumulus to Boundary Layer Cumulus with a Mesoscale Model
A case of coastal California summer season boundary layer cloud has been simulated with the U.S. Navy Coupled Ocean�Atmosphere Mesoscale Prediction System and the results analyzed in the context of consistency with conclusions derived from large ...
David B. Mechem; Yefim L. Kogan
The Marine Boundary Layer in the Vicinity of an Ocean Front
Aircraft observations obtained during the Frontal Air�Sea Interaction Experiment (FASINEX) are used to investigate the structure of the marine atmospheric boundary layer in the vicinity of an ocean front. A quasi-stationary sea surface ...
David P. Rogers
Climatology of Warm Boundary Layer Clouds at the ARM SGP Site and Their Comparison to Models
A 4-yr climatology (1997�2000) of warm boundary layer cloud properties is developed for the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) site. Parameters in the climatology include cloud ...
Manajit Sengupta; Eugene E. Clothiaux; Thomas P. Ackerman
Empirical Orthogonal Function Analysis of the Weakly Convective Atmospheric Boundary Layer. Part I: Eddy Structures
Three-dimensional empirical orthogonal functions (EOFs), representing atmospheric turbulence structures, are determined from a large-eddy simulation of a weakly convective, planetary boundary layer. The method of analysis is based on Lumley's ...
D. Keith Wilson
Asymmetric Hurricane Boundary Layer Structure from Dropsonde Composites in Relation to the Environmental Vertical Wind Shear
This study investigates the asymmetric structure of the hurricane boundary layer in relation to the environmental vertical wind shear in the inner core region. Data from 1878 GPS dropsondes deployed by research aircraft in 19 hurricanes are ...
Jun A. Zhang; Robert F. Rogers; Paul D. Reasor; Eric W. Uhlhorn; Frank D. Marks Jr.
Application of the E � ? Turbulence Closure Model to the Neutral and Stable Atmospheric Boundary Layer
In the E � ? turbulence model an eddy-exchange coefficient is evaluated from the turbulent kinetic energy E and viscous dissipation ?. In this study we will apply the E � ? model to the stable and neutral atmospheric boundary layer. A discussion ...
P. G. Duynkerke
A Model of Marine Boundary-Layer Cloudiness for Mesoscale Applications
A one-dimensional version of a multilevel mesoscale model is used to represent the cloud-topped boundary layer (CTBL). Turbulent exchanges are parameterized with a prognostic equation for the turbulent kinetic energy and an improved length-scale ...
Peter Bechtold; Jean Pierre Pinty; Charles Fravalo
Turbulence Characteristics and Dissipation Estimates in the Coastal Ocean Bottom Boundary Layer from PIV Data
Turbulence characteristics in the coastal ocean bottom boundary layer are measured using a submersible Particle Image Velocimetry (PIV) system with a sample area of 20 � 20 cm2. Measurements are performed in the New York Bight at elevations ...
P. Doron; L. Bertuccioli; J. Katz; T. R. Osborn
A time-varying subsidence parameterization for the atmospheric boundary layer
This study examines the effect of a time-varying parameterization for subsidence in the atmospheric boundary layer (ABL) on a one-dimensional coupled land-atmosphere model. Measurements of large-scale divergence in the ABL ...
Flagg, David D. (David Douglas)
Relating Eulerian and Lagrangian Statistics for the Turbulent Dispersion in the Atmospheric Convective Boundary Layer
Eulerian and Lagrangian statistics in the atmospheric convective boundary layer (CBL) are studied by means of large eddy simulation (LES). Spectra analysis is performed in both the Eulerian and Lagrangian frameworks, autocorrelations are ...
Alessandro Dosio; Jordi Vil� Guerau de Arellano; Albert A. M. Holtslag; Peter J. H. Builtjes
A UHF Wind Profiler for the Boundary Layer: Brief Description and Initial Results
In this paper we describe a boundary layer radar recently developed at NOAA's Aeronomy Laboratory. This radar extends wind profiler technology by using a small, relatively inexpensive radar to provide continuous, high-resolution wind measurements ...
W. L. Ecklund; D. A. Carter; B. B. Balsley
A Modeling Study on the Fair Weather Marine Boundary Layer of the GATE
A three-dimensional ensemble-mean atmospheric model, with simplified second-moment turbulence closure equations and a statistical treatment for the condensation process, is used to simulate a fair weather marine boundary layer observed during the ...
T. Yamada; C-Y. J. Kao
Numerical Modeling of the Turbulent Fluxes of Chemically Reactive Trace Gases in the Atmospheric Boundary Layer
Turbulent fluxes of chemically reactive trace gases in the neutral atmospheric boundary layer (ABL) were simulated with a one-dimensional, coupled diffusion-chemistry model. The effects of rapid chemical reactions were included with a suite of ...
W. Gao; M. L. Wesely
Relating Satellite-Observed Cloud Properties from MODIS to Meteorological Conditions for Marine Boundary Layer Clouds
This study examines 6 yr of cloud properties observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Terra satellite in five prominent marine boundary layer (MBL) cloud regions (California, Peru, Canary, Angola, ...
Guang J. Zhang; Andrew M. Vogelmann; Michael P. Jensen; William D. Collins; Edward P. Luke
The influence of submeso processes on stable boundary layer similarity relationships
Previous observational studies in the stable boundary layer diverge appreciably on the values of dimensionless ratios between turbulence-related quantities and on their stability dependence. In the present study, the hypothesis that such ...
Ot�vio C. Acevedo; Felipe D. Costa; Pablo E. S. Oliveira; Franciano S. Puhales; Gerv�sio A. Degrazia; D�bora R. Roberti
Intermittency and the Organization of Turbulence in the Near-Neutral Marine Atmospheric Boundary Layer
Aircraft data from the JASIN Experiment have been used to examine the role that intermittency plays in turbulent transfer in the near-neutral marine atmospheric boundary layer. Conditional sampling, using the time-varying dissipation rate as an ...
William J. Shaw; Joost A. Businger
Finding Boundary Layer Top: Application of a Wavelet Covariance Transform to Lidar Backscatter Profiles
Several recent studies have utilized a Haar wavelet covariance transform to provide automated detection of the boundary layer top from lidar backscatter profiles by locating the maximum in the covariance profiles. This approach is effective where ...
Ian M. Brooks
An Eulerian Model of Dispersion in the Convective Boundary Layer Using Explicit Periodic Advections
The authors have developed a relatively simple, first-order closure, Eulerian diffusion model, in which turbulent coherent structures of the convective boundary layer are explicitly included as periodic velocities imposed on a stationary and ...
John J. Carroll; Ming Liu
Seasonal Variation of the Physical Properties of Marine Boundary Layer Clouds off the California Coast
Marine boundary layer (MBL) clouds can significantly regulate the sensitivity of climate models, yet they are currently poorly simulated. This study aims to characterize the seasonal variations of physical properties of these clouds and their ...
Wuyin Lin; Minghua Zhang; Norman G. Loeb
Observations of Vertical Velocity Skewness within the Marine Stratocumulus-Topped Boundary Layer
During June and July 1987 the First ISCCP (International Satellite Cloud Climatology Project) Regional Experiment (FIRE) was conducted within the marine stratocumulus-topped boundary layer off the coast of California. One of the goals of the ...
Kerry A. Moyer; George S. Young
Boundary Layer Energy Transport and Cumulus Development over a Heated Mountain: An Observational Study
Aircraft and surface measurements of the boundary layer transport of mass and moisture toward an isolated, heated mountain are presented. The data were collected around the Santa Catalina Mountains in Arizona, 20�30 km in diameter, during the ...
J. Cory Demko; Bart Geerts; Qun Miao; Joseph A. Zehnder
Characteristics of the Near-Surface Boundary Layer within a Mountain Valley during Winter
Within mountainous regions, estimating the exchange of sensible heat and water vapor between the surface and the atmosphere is an important but inexact endeavor. Measurements of the turbulence characteristics of the near-surface boundary layer in ...
Warren Helgason; John W. Pomeroy
A Simple Model for Pollution Dispersion in a Convective Boundary Layer
A simplified model for dispersion in a convective boundary layer is presented and is used to diagnose crosswind-integrated concentrations, ground-level concentrations, and vertical plume spread over flat terrain for various release heights. The ...
Roland Stull; Bruce Ainslie
Mechanism of Heating and the Boundary Layer over the Tibetan Plateau
The structure of the boundary layer and the mechanism of heating over the Tibetan Plateau are examined using the data obtained from the First GARP (Global Atmospheric Research Program) Global Experiment and the Chinese Qinghai�Xizang (Tibet) ...
Michio Yanai; Chengfeng Li
Large Eddy Simulation of an Inhomogeneous Atmospheric Boundary Layer under Neutral Conditions
Flow structures in an inhomogeneous neutrally stratified atmospheric boundary layer flow, obtained from large eddy simulation, are analyzed and compared with homogeneous case counterparts. The inhomogeneity is imposed in the streamwise direction ...
Ching-Long Lin; John W. Glendening
A Combined Eddy-Diffusivity Mass-Flux Approach for the Convective Boundary Layer
A better conceptual understanding and more realistic parameterizations of convective boundary layers in climate and weather prediction models have been major challenges in meteorological research. In particular, parameterizations of the dry ...
A. Pier Siebesma; Pedro M. M. Soares; Jo�o Teixeira
Convective Evolution and Merger in the FACE Experimental Area: Mesoscale Convection and Boundary Layer Interactions
This paper investigates the interactions between the various scales of motion and, specifically, the inter-actions between convection and the surface boundary layer in the development of a mesoscale convective system within the Florida Area ...
John B. Cunning; Ronald L. Holle; Patrick T. Gannon; Andrew I. Watson
An Approximate Footprint Model for Flux Measurements in the Convective Boundary Layer
An explicit footprint model for flux measurements of passive scalars in the lower part of the convective boundary layer (CBL) is introduced. A simple footprint model is derived analytically in an idealized CBL. The simple model can simulate the ...
Weiguo Wang; Kenneth J. Davis; Daniel M. Ricciuto; Martha P. Butler
Evaluations of Diagnostic Marine Boundary-Layer Models Applied to Hurricanes
Four diagnostic marine boundary-layer models are evaluated for applicability to the hurricane regime. The goat was to develop an operational method of estimating surface variables with research aircraft flight-level (500 m) data. Evaluation ...
Boundary Layer Control of Buoyant Coastal Currents and the Establishment of a Shelfbreak Front
The bottom boundary layer exerts a powerful control over buoyant coastal currents that contact the bottom, providing a mechanism for trapping density fronts along isobaths. Recent observations suggest that this mechanism may play a role in ...
David C. Chapman
Surface Heterogeneity Effects on Regional-Scale Fluxes in Stable Boundary Layers: Surface Temperature Transitions
Large-eddy simulation, with recently developed dynamic subgrid-scale models, is used to study the effect of heterogeneous surface temperature distributions on regional-scale turbulent fluxes in the stable boundary layer (SBL). Simulations are ...
Rob Stoll; Fernando Port�-Agel
Turbulence Spectra and Dissipation Rates in a Wind Tunnel Model of the Atmospheric Convective Boundary Layer
A model of the atmospheric convective boundary layer (CBL) is realized in the thermally stratified wind tunnel of the Institute of Hydrology and Water Resources, University of Karlsruhe. Further experimental results from this model are presented. ...
Rolf Kaiser; Evgeni Fedorovich
A Volume-Imaging Radar Wind Profiler for Atmospheric Boundary Layer Turbulence Studies
This paper describes the turbulent eddy profiler (TEP), a volume-imaging, UHF radar wind profiler designed for clear-air measurements in the atmospheric boundary layer on scales comparable to grid cell sizes of large eddy simulation models. TEP ...
James B. Mead; Geoffrey Hopcraft; Stephen J. Frasier; Brian D. Pollard; Christopher D. Cherry; Daniel H. Schaubert; Robert E. McIntosh
Drizzle in Stratiform Boundary Layer Clouds. Part I: Vertical and Horizontal Structure
Detailed observations of stratiform boundary layer clouds on 12 days are examined with specific reference to drizzle formation processes. The clouds differ considerably in mean thickness, liquid water path (LWP), and droplet concentration. Cloud-...
Observations of Small-Scale Turbulence and Energy Dissipation Rates in the Cloudy Boundary Layer
Tethered balloon�borne measurements with a resolution in the order of 10 cm in a cloudy boundary layer are presented. Two examples sampled under different conditions concerning the clouds' stage of life are discussed. The hypothesis tested here ...
Holger Siebert; Katrin Lehmann; Manfred Wendisch
Large Eddy Simulation of Turbulent Flow in a Marine Convective Boundary Layer with Snow
A large eddy simulation (LES) model, with ice phase included, has been used to study the marine convective boundary layer filled with snow. Extensions to Moeng's LES model include the diagnosis of cloud ice mixing ratio, snow precipitation, and ...
Guan-Shu Rao; Ernest M. Agee
Mean Structure of the Nocturnal Boundary Layer under Strong and Weak Wind Conditions: EPRI Case Study
The major objective of this study was to analyze the mean structure and evolution of the nocturnal boundary layer (NBL) under strong and weak wind conditions. Meteorological data collected during the plume-validation experiment conducted by the ...
T. B. P. S. Rama V. Krishna; Maithili Sharan; S. G. Gopalakrishnan; Aditi
The Impact of Wet Soil and Canopy Temperatures on Daytime Boundary�Layer Growth
The impact of very wet soil and canopy temperatures on the surface sensible heat flux, and on related daytime boundary-layer properties is evaluated. For very wet soils, two winter situations are considered, related to significant changes in soil ...
M. Segal; J. R. Garratt; G. Kallos; R. A. Pielke
Thunderstorm Initiation, Organization, and Lifetime Associated with Florida Boundary Layer Convergence Lines
The initiation, organization, and longevity of thunderstorms associated with boundary layer convergence lines in the Cape Canaveral, Florida, vicinity are examined using data from the Convection and Precipitation/Electrification (CaPE) ...
James W. Wilson; Daniel L. Megenhardt
Numerical Simulations of a Stratocumulus-Capped Boundary Layer Observed over Land
Detailed observations of both mean and turbulence fields of an anticyclonic, quasi-steady state, stratocumulus-capped boundary layer obtained with ground-based and balloonborne equipment during the night of 19/20 November 1976 at Cardington, ...
Chih-Yue Jim Kao; Tetsuji Yamada
A 6-yr Climatology of Fronts Affecting Helsinki, Finland, and Their Boundary Layer Structure
A 6-yr climatology of the frequency, characteristics, and boundary layer structure of synoptic-scale fronts in Helsinki, Finland, was created using significant weather charts and observations from a 327-m-tall mast and from the Station for ...
Victoria A. Sinclair
Spectral Estimates of Bed Shear Stress at Subcritical Reynolds Numbers in a Tidal Boundary Layer
Velocity measurements from five levels in the constant-stress region of a neutrally stratified turbulent boundary layer are used to show that below a critical height the spectral energy density in the inertial subrange remains constant at a ...
Malcolm O. Green
Validation of a UV to RF High Spectral Resolution Atmospheric Boundary Layer Characterization Tool
This paper demonstrates the capability of the Laser Environmental Effects Definition and Reference (LEEDR) model to accurately characterize the meteorological parameters and radiative transfer effects of the atmospheric boundary layer with surface ...
Steven T. Fiorino; Robb M. Randall; Michelle F. Via; Jarred L. Burley
Boundary layer convergence induced by strong winds across a midlatitude SST front
Recent studies indicate that midlatitude SST fronts� influence extends through the marine atmospheric boundary layer (MABL) into the free atmosphere, with implications for climate variability. To better understand the mechanisms of this ocean-to-...
Thomas Kilpatrick; Niklas Schneider; Bo Qiu
Large-Eddy Simulation of Roll Vortices in a Hurricane Boundary Layer
For the last decade, horizontal roll vortices have been often observed in hurricane boundary layers (HBLs). In this study, a large-eddy simulation is performed to explore the formation mechanism of the horizontal roll vortices and their ...
Mikio Nakanishi; Hiroshi Niino
Multiple-Doppler Radar Observations of the Evolution of Vorticity Extrema in a Convective Boundary Layer
Overdetermined, dual-Doppler wind syntheses are used to document the evolution, structure, and dynamics of vertical vorticity extrema observed in a convective boundary layer during the 12 June 2002 International H2O Project (IHOP) mission. ...
Paul Markowski; Christina Hannon
Investigation of Regional and Seasonal Variations in Marine Boundary Layer Cloud Properties from MODIS Observations
To aid in understanding the role that marine boundary layer (MBL) clouds play in climate and assist in improving their representations in general circulation models (GCMs), their long-term microphysical and macroscale characteristics are ...
Michael P. Jensen; Andrew M. Vogelmann; William D. Collins; Guang J. Zhang; Edward P. Luke
Thermodynamic Variability within the Convective Boundary Layer Due to Horizontal Convective Rolls
Data from the Convection and Precipitation/Electrification (CaPE) Experiment conducted during the summer of 1991 are used to examine and quantify the horizontal variability of temperature and moisture within the convective boundary layer (CBL). ...
Tammy M. Weckwerth; James W. Wilson; Roger M. Wakimoto
The Atmospheric Boundary Layer above the Agulhas Current during Alongcurrent Winds
The response of the marine atmospheric boundary layer to the strong sea surface temperature (SST) gradient across the warm Agulhas Current was studied in the Agulhas Current Air�Sea Exchange Experiment, south of Port Alfred, South Africa. ...
M. Rouault; A. M. Lee-Thorp; J. R. E. Lutjeharms
Integral Scales for the Nocturnal Boundary Layer. Part II: Heat Budget, Transport and Energy Implications
In Part I, external forcings such as pressure gradient, terrain roughness and imposed cooling were used to forecast the thickness and strength of an exponentially-shaped (ES) nocturnal boundary layer (NBL) temperature profile. In Part II, it is ...
Roland B. Stull
A Comparison of Ekman Pumping in Approximate Models of the Accelerating Planetary Boundary Layer
Several theories of the planetary boundary layer that retain the flow accelerations in approximate form are compared. Two special test cases focus on the role of either local or convective accelerations. The semigeotriptic theory of Cullen ...
Peter R. Bannon
A Cloud-Resolving Model with an Adaptive Vertical Grid for Boundary Layer Clouds
Accurate cloud-resolving model simulations of cloud cover and cloud water content for boundary layer clouds are difficult to achieve without vertical grid spacing well below 100 m, especially for inversion-topped stratocumulus. The need for fine ...
Roger Marchand; Thomas Ackerman
Asymmetric Behavior of an Oceanic Boundary Layer above a Sloping Bottom
The effects of stratification, planetary rotation and a sloping bottom combine to produce an asymmetric response in which the characteristics of an oceanic bottom boundary layer depend on the direction, in addition to the magnitude, of the along-...
J. H. Trowbridge; S. J. Lentz
Observations and Numerical Model Simulations of the Atmospheric Boundary Layer in the Santa Barbara Coastal Region
Observations of boundary-layer flow within the Santa Barbara region taken on 20 September 1985 revel the presence of a wide variety of flow features, including mesoscale wind vortices sea/land breezes, and thermally driven upslope/downslope ...
J. M. Wilczak; W. F. Dabberdt; R. A. Kropfli
Atmospheric Boundary-Layer Properties Affecting Wind Forecasting in Coastal Regions
Atmospheric boundary-layer properties and processes in gulf and coastal regions have special characteristics that are important in forecasting winds and ocean forcing. Accurate coastal-wind predictions require knowledge of local responses to a ...
Kenneth L. Davidson; Patricia J. Boyle; Peter S. Guest
Cluster Analysis: A new approach applied to Lidar measurements for Atmospheric Boundary Layer height estimation
Several procedures are widely applied to estimate the Atmospheric Boundary Layer (ABL) top height by using aerosols as tracers from lidar measurements. These methods represent different mathematical approaches relying on either the abrupt step of ...
Daniel Toledo; Carmen C�rdoba-Jabonero; Manuel Gil-Ojeda
Scalar Turbulence in Convective Boundary Layers by Changing the Entrainment Flux
A large-eddy simulation model is adopted to investigate the evolution of scalars transported by atmospheric cloud-free convective boundary layer flows. Temperature fluctuations due to the ground release of sensible heat and concentration ...
Alessandra S. Lanotte; Irene M. Mazzitelli
Observed Boundary Layer Wind Structure and Balance in the Hurricane Core. Part II: Hurricane Mitch
Part I of this paper presented a detailed analysis of the boundary layer of Hurricane Georges (1998), based mainly on the newly available high-resolution GPS dropsonde data. Here, similar techniques and data are used to study Hurricane Mitch (...
The Boundary Layer Winds in Hurricanes Danielle (1998) and Isabel (2003)
This paper describes the boundary layer wind structure and dynamics of Hurricanes Danielle (1998) and Isabel (2003), based on the analysis of high-resolution global positioning system dropwindsonde data and simulation of the flow by a three-...
Juliane Schwendike; Jeffrey D. Kepert
An Observational Case for the Prevalence of Roll Vortices in the Hurricane Boundary Layer
Doppler velocity data from Weather Surveillance Radar-1988 Doppler (WSR-88D) radars during four hurricane landfalls are analyzed to investigate the presence of organized vortices in the hurricane boundary layer (HBL). The wavelength, depth, ...
Ian Morrison; Steven Businger; Frank Marks; Peter Dodge; Joost A. Businger
Parameterization of Surface Heat Fluxes above Forest with Satellite Thermal Sensing and Boundary-Layer Soundings
Satellite-derived surface temperature measurements can be used in conjunction with temperature and wind soundings in the boundary layer to determine the surface sensible heat flux from forests at the regional scale. The underlying formulation is ...
Wilfried Brutsaert; A. Y. Hsu; Thomas J. Schmugge
Leeside Boundary Layer Confluence and Afternoon Thunderstorms over Mayaguez, Puerto Rico
The midsummer boundary layer (BL) circulation and afternoon thunderstorm convection on the lee side of Puerto Rico is studied using observations and high-resolution models. Satellite infrared data help to identify cases on 5 and 14 June 2010 when ...
Mark R. Jury; Sen Chiao
Modification of the Atmospheric Boundary Layer by a Small Island: Observations from Nauru
Nauru, a small island in the tropical Pacific, generates cloud plumes that may grow to over 100-km lengths. This study uses observations to examine the mesoscale disturbance of the marine atmospheric boundary layer by the island that produces ...
Stuart Matthews; J�rg M. Hacker; Jason Cole; Jeffrey Hare; Charles N. Long; R. Michael Reynolds
Climatic Equilibrium of the Atmospheric Convective Boundary Layer over a Tropical Ocean
A one-dimensional thermodynamic model for a partially mixed, partly cloudy, convective boundary layer (CBL) is coupled to a radiation model to compute equilibrium solutions for a tropical CBL and troposphere in energy balance over the ocean. For ...
Alan K. Betts; W. Ridgway
Modification of a Commercial Condensation Particle Counter for Boundary Layer Balloon-Borne Aerosol Studies
A commercial battery-driven condensation particle counter (TSI-8020) was modified for use in a lightweight payload for tethered balloons to study new particle formation in the planetary boundary layer. After modifications, the instrument was ...
Jost Heintzenberg; Alfred Wiedensohler; Stefan K�tz
A Mathematical Model of the Ocean Boundary Layer under Drifting Melting ice
A mathematical model of the ocean boundary layer under drifting melting ice is formulated, verified, and applied. The model is based on the conservation equations for heat, salt, and momentum and uses turbulence models to achieve closure. Novel ...
U. Svensson; A. Omstedt
Airship Measurements of Ship�s Exhaust Plumes and Their Effect on Marine Boundary Layer Clouds
High-resolution aerosol, trace gas, and cloud microphysical measurements were made from an airship during transects across ships exhaust plumes advecting downwind of ships in the marine boundary layer (MBL). This study was part of the Office of ...
G. M. Frick; W. A. Hoppel
Ultralight Sounder: An Airborne System for Studying the Planetary Boundary Layer
Until recently, investigations of the temperature structure of the planetary boundary layer have been confined to the use of balloon soundings (tethered balloon sondes, rawinsondes), disposable drop-sondes, or high performance instrumented ...
Randolph D. Borys; Kapin Tan; William Cotton
Surface Temperature Calculation in Atmospheric Circulation Models with Coarse Resolution of the Boundary Layer
A parameterization of the surface nocturnal inversion of temperature is proposed to enable atmospheric circulation models to handle the surface energy budget without having to resolve the boundary layer. The scheme allows a wide range of vertical ...
Yves Delage
Lidar-Observed Stress Vectors and Veer in the Atmospheric Boundary Layer
We demonstrate that a pulsed wind lidar is a reliable instrument for measuring angles between horizontal vectors of significance in the atmospheric boundary layer. We consider three different angles: the wind turning, the angle between the stress ...
Jacob Berg; Jakob Mann; Edward G. Patton
A Case Study of Ship Track Formation in a Polluted Marine Boundary Layer
A case study of the effects of ship emissions on the microphysical, radiative, and chemical properties of polluted marine boundary layer clouds is presented. Two ship tracks are discussed in detail. In situ measurements of cloud drop size ...
Kevin J. Noone; Doug W. Johnson; Jonathan P. Taylor; Ronald J. Ferek; Tim Garrett; Peter V. Hobbs; Philip A. Durkee; Kurt Nielsen; Elisabeth �str�m; Colin O�Dowd; Michael H. Smith; Lynn M. Russell; Richard C. Flagan; John H. Seinfeld; Lieve De Bock; Ren� E. Van Grieken; James G. Hudson; Ian Brooks; Richard F. Gasparovic; Robert A. Pockalny
Some Observational Evidence for Dry Soils Supporting Enhanced Relative Humidity at the Convective Boundary Layer Top
The tendency of the relative humidity at the top of a clear convective boundary layer (RHtop) is studied as an indicator of cloud formation over a semiarid region within the conceptual framework introduced by Ek and Holtslag. Typically the ...
D. Westra; G. J. Steeneveld; A. A. M. Holtslag
Large-Scale Atmospheric Forcing by Southeast Pacific Boundary Layer Clouds: A Regional Model Study
A regional model is used to study the radiative effect of boundary layer clouds over the southeast Pacific on large-scale atmosphere circulation during August�October 1999. With the standard settings, the model simulates reasonably well the large-...
Yuqing Wang; Shang-Ping Xie; Bin Wang; Haiming Xu
Dispersion of a Passive Tracer in Buoyancy- and Shear-Driven Boundary Layers
By means of finescale modeling [large-eddy simulation (LES)], the combined effect of thermal and mechanical forcing on the dispersion of a plume in a convective boundary layer is investigated. Dispersion of a passive tracer is studied in various ...
Alessandro Dosio; Jordi Vil�-Guerau de Arellano; Albert A. M. Holtslag; Peter J. H. Builtjes
A PDF-Based Microphysics Parameterization for Simulation of Drizzling Boundary Layer Clouds
Formulating the contribution of subgrid-scale (SGS) variability to microphysical processes in boundary layer and deep convective cloud parameterizations is a challenging task because of the complexity of microphysical processes and the lack of ...
Anning Cheng; Kuan-Man Xu
A Dual Mass Flux Framework for Boundary Layer Convection. Part II: Clouds
This paper presents the extension of the eddy diffusivity mass flux (EDMF) framework for turbulent transport into the statistical modeling of boundary layer clouds. The advection�diffusion decomposition that defines EDMF is projected onto the ...
Roel A. J. Neggers
A PDF Dispersion Model for Buoyant Plumes in the Convective Boundary Layer
A probability density function (PDF) dispersion model is presented for buoyant plumes in the convective boundary layer (CBL), where the mean concentration field C is obtained from the PDFs py and pz of tracer particle position in the lateral y ...
J. C. Weil; L. A. Corio; R. P. Brower
How Does the Boundary Layer Contribute to Eyewall Replacement Cycles in Axisymmetric Tropical Cyclones?
Three diagnostic models of the axisymmetric tropical cyclone boundary layer, with different levels of approximation, are applied to the problem of tropical cyclones with concentric eyewalls. The outer eyewall is shown to have an inherently ...
Diapycnal Transport and Mixing Efficiency in Stratified Boundary Layers near Sloping Topography
The interaction of shear, stratification, and turbulence in boundary layers on sloping topography is investigated with the help of an idealized theoretical model, assuming uniform bottom slope and homogeneity in the upslope direction. It is shown ...
Lars Umlauf; Hans Burchard
Observational Study of a Convective Internal Boundary Layer over Lake Michigan
Using aircraft data collected during the University of Chicago Lake-Effect Snow Storm project, the results of a case study of the convective thermal internal boundary layer (TIBL) over Lake Michigan are presented. An intense cold air outbreak on ...
Sam S. Chang; Roscoe R. Braham Jr.
Evaluation of Numerical Predictions of Boundary Layer Structure during the Lake Michigan Ozone Study
The performance of two types of turbulence closures is compared in a 3D numerical investigation of an episode with poor air quality. The first is the Blackadar boundary layer scheme, which has a nonlocal closure for unstable conditions. The ...
Perry C. Shafran; Nelson L. Seaman; George A. Gayno
A Lagrangian Long-Range Transport Model with Atmospheric Boundary Layer Chemistry
The present paper reports on the combination of a chemical model for the gas phase chemistry of the atmospheric boundary layer, with a Lagrangian model for the long-range transport of air pollutants. The resulting combined chemistry/transport ...
Anton Eliassen; J�rgen Saltbones; Frode Stordal; �ystein Hov; Ivar S. A. Isaksen; Frode Stordal
How does the boundary layer contribute to eyewall replacement cycles in axisymmetric tropical cyclones?
Plume Dispersion in the Convective Boundary Layer. Part I: CONDORS Field Experiment and Example Measurements
Project CONDORS (CONvective Diffusion Observed by Remote Sensors) measured the dispersion of a nonbuoyant plume in the highly convective boundary layer. Laboratory and numerical models have predicted vertical profiles of a passive tracer that are ...
W. L. Eberhard; W. R. Moninger; G. A. Briggs
Turbulence and Radiation in Stratocumulus Topped Marine Boundary Layers: A Case Study from VOCALS-REx
Observations made during a 24 hour period as part of the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) are analyzed to study the radiation and turbulence associated with stratocumulus topped marine boundary layer (BL). ...
Virendra P. Ghate; Bruce A. Albrecht; Mark A. Miller; Alan Brewer; Christopher W. Fairall
The Numerical Representation of Entrainment in Parameterizations of Boundary Layer Turbulent Mixing
Problems have been identified with parameterizations of convective boundary layers, in particular with their numerical treatment of the capping inversion. It is shown that the turbulence scheme can combine with the numerical representation of ...
A. P. Lock
Dynamical Analysis of the Boundary Layer and Surface Wind Responses to Mesoscale SST Perturbations
The dynamical response of the marine atmospheric boundary layer (MABL) to mesoscale sea surface temperature (SST) perturbations is investigated over the Agulhas Return Current during winter from a 1-month, high-resolution, three-dimensional ...
Larry W. O�Neill; Steven K. Esbensen; Nicolai Thum; Roger M. Samelson; Dudley B. Chelton
The Impact of Chemistry on Flux Estimates in the Convective Boundary Layer
Different higher-order flux closures are compared for two chemistry cases using a large eddy simulation (LES) model for the convective atmospheric boundary layer. Both a simple chemistry case and a photochemistry case more representative for ...
Arthur C. Petersen
An Indirect Estimation of Convective Boundary Layer Structure for Use in Pollution Dispersion Models
Dispersion models of the convectively driven atmospheric boundary layer (ABL) often require as input meteorological parameters that are not routinely measured. These parameters usually include the surface fluxes of heat and momentum ?Cpw???and ?u?w?, the ...
James M. Wilczak; Mary Sue Phillips
An Investigation of the Boundary Layer Dynamics of Sardinia Island under Sea-Breeze Conditions
A numerical mesoscale model is used to study the wind field and the boundary layer structure of the island of Sardinia during typical summer conditions. The numerical model is three-dimensional and employs a higher-order turbulence closure ...
Dimitrios Melas; Alfredo Lavagnini; Anna-Maria Sempreviva
Meteorological and Astronomical Influences on Radar Reflectivity in the Convective Boundary Layer
Observations are presented of time-varying radar reflectivity during a partial solar eclipse in Oklahoma. The measurements from a radar of 10-cm wavelength, were obtained in the clear-air boundary layer. The reflectivity changes closely follow ...
Robert M. Rabin; Richard J. Doviak
Estimating the Orientation and Spacing of Midlatitude Linear Convective Boundary Layer Features: Cloud Streets
Linear features in a clear convective boundary layer (CBL) over the North Atlantic Ocean were studied during a weak cold air outbreak using a down-looking airborne lidar. Sequential lidar profiles were placed together and color coded to provide ...
S. H. Melfi; Stephen P. Palm
A Model for the Turbulent Structure of the Stratocumulus�Topped Atmospheric Boundary Layer
A multilevel ensemble-averaged model has been developed to study the cloud-topped atmospheric boundary layer (ABL). Turbulence closure is formulated by using an equation for the turbulent kinetic energy and either a diagnostic formulation of the ...
P. G. Duynkerke; A. G. M. Driedonks
Exploring the Possible Role of Small-Scale Terrain Drag on Stable Boundary Layers over Land
This paper addresses the possible role of unresolved terrain drag, relative to the turbulent drag on the development of the stable atmospheric boundary layer over land. Adding a first-order estimate for terrain drag to the turbulent drag appears ...
G. J. Steeneveld; A. A. M. Holtslag; C. J. Nappo; B. J. H. van de Wiel; L. Mahrt
Transient Evolution of Langmuir Turbulence in Ocean Boundary Layers Driven by Hurricane Winds and Waves
A large-eddy simulation (LES) model, which adopts wave-averaged equations with vortex force, is used to investigate Langmuir turbulence and ocean boundary layer (OBL) dynamics in high-wind hurricane conditions. The temporally evolving spatially ...
Peter P. Sullivan; Leonel Romero; James C. McWilliams; W. Kendall Melville
A Modeling Study of the Effects of Inhomogeneous Surface Fluxes on Boundary-Layer Properties
A numerical modeling study was conducted to examine the response of the atmospheric boundary layer to inhomogeneous surface fluxes. The study was used to extend the results obtained from a field experiment carried out in spring 1992 in north-...
Shiyuan Zhong; J. C. Doran
An Embedded Bottom Boundary Layer Formulation for Z-Coordinate Ocean Models
An embedded bottom boundary layer (EBBL) scheme is developed to improve the bottom topographic representation in z-coordinate ocean general circulation models. The EBBL scheme is based on the combined techniques of an embedded topography-...
Y. Tony Song; Yi Chao
Evaluation of Boundary Layer Similarity Theory for Stable Conditions in CASES-99
The Monin�Obukhov similarity theory and a generalized formulation of the mixing length for the stable boundary layer are evaluated using the Cooperative Atmosphere�Surface Exchange Study-1999 (CASES-99) data. The large-scale wind forcing is ...
Kyung-Ja Ha; Yu-Kyung Hyun; Hyun-Mi Oh; Kyung-Eak Kim; Larry Mahrt
Advances in the visualization and analysis of boundary layer flow in swimming fish
In biology, the importance of fluid drag, diffusion, and heat transfer both internally and externally, suggest the boundary layer as an important subject of investigation, however, the complexities of biological systems ...
Anderson, Erik J
Observations of Turbulence Mixing and Vorticity in a Littoral Surface Boundary Layer
Measurements of small-scale vorticity, turbulence velocity, and dissipation rates of turbulence kinetic energy ? were taken in a littoral fetch-limited surface wave boundary layer. Drifters deployed on the surface formed convergence streaks with ...
R-C. Lien; B. Sanford; W-T. Tsai
Numerical Simulation of Transitions in Boundary Layer Convective Structures in a Lake-Effect Snow Event
Numerical simulations are used to study transitions between boundary layer rolls and more cellular convective structures observed during a lake-effect snow event over Lake Michigan on 17 December 1983. Weak lake-effect nonroll convection was ...
Kevin A. Cooper; Mark R. Hjelmfelt; Russell G. Derickson; David A. R. Kristovich; Neil F. Laird
Synoptic Forcing Of Coastal-Trapped Disturbances in the Marine Atmospheric Boundary Layer
Motivated by recent observations along the west coast of the United States, the authors investigate the generation and propagation of coastal-trapped disturbances in the marine atmospheric boundary layer. Analytic solutions are obtained in a ...
A. M. Rogerson; R. M. Samelson
Radar Observations of Humidity Variability in and above the Marine Atmospheric Boundary Layer
Humidity variability at the top of the marine atmospheric boundary layer and in the overlying free troposphere was examined using data collected during the marine stratocumulus phase of the First Regional Experiment (FIRE) of the International ...
Allen B. White; C. W. Fairall; Dennis W. Thomson
Wind Direction Dependence of Atmospheric Boundary Layer Turbulence Parameters in the Urban Roughness Sublayer
A variety of atmospheric boundary layer parameters are examined as a function of wind direction in both urban and suburban settings in Oklahoma City, Oklahoma, derived from measurements during the Joint Urban 2003 field campaign. Heterogeneous ...
Cheryl Klipp
Deep convection triggering by boundary layer thermals. Part 1: LES analysis and stochastic triggering formulation
This paper proposes a new formulation of the deep convection triggering for GCM (General Circulation Model) convective parameterizations. This triggering is driven by evolving properties of the strongest boundary-layer thermals. To investigate ...
Nicolas Rochetin; Fleur Couvreux; Jean-Yves Grandpeix; Catherine Rio
Parameterization of the Dry Convective Boundary Layer Based on a Mass Flux Representation of Thermals
Presented is a mass flux parameterization of vertical transport in the convective boundary layer. The formulation of the new parameterization is based on an idealization of thermal cells or rolls. The parameterization is validated by comparison ...
Fr�d�ric Hourdin; Fleur Couvreux; Laurent Menut
Heat Energy Balance in the Convective Atmospheric Boundary Layer at Xianghe (Beijing Area), China
A simple and physically consistent expression for the turbulent heat flux equation in the convective atmospheric boundary layer (CABL) has been suggested by Holtslag and Moeng in 1991. In their equation, valid under quasi-steady states and ...
M. W. Qian; A. Longhetto; C. Cassardo; C. Giraud; Z. X. Hong; W. D. Luo; Y. J. Zhao
The Structure of the Unstable Marine Boundary Layer Viewed by Lidar and Aircraft Observations
The combination of vertical lidar and in situ meteorological observations from two aircraft provide an unprecedented view of the marine atmospheric boundary layer (MABL) during a cold air outbreak. To a first approximation, the lidar reflectivity ...
David Atlas; Bernard Walter; Shu-Hsien Chou; P. J. Sheu
Parameterizing Grid-Averaged Longwave Fluxes for Inhomogeneous Marine Boundary Layer Clouds
This paper examines the relative impacts on grid-averaged longwave flux transmittance (emittance) for marine boundary layer (MBL) cloud fields arising from horizontal variability of optical depth ? and cloud sides. First, using fields of Landsat-...
Howard W. Barker; Bruce A. Wielicki
Dynamics of Sheared Convective Boundary Layer Entrainment. Part I: Methodological Background and Large-Eddy Simulations
The reported study examines the dynamics of entrainment and its effects on the evolution of the dry atmospheric convective boundary layer (CBL) when wind shear is present. The sheared CBL can be studied by means of direct measurements in the ...
Robert J. Conzemius; Evgeni Fedorovich
Conditional Sampling of Updrafts and Downdrafts in the Marine Atmospheric Boundary Layer
The properties of updrafts and downdrafts in the lower third of the marine atmospheric boundary layer (MABL) over the central Pacific Ocean are investigated using a conditional sampling technique. When the drafts are classified according to their ...
Siri Jodha Singh Khalsa; Gary K. Greenhut
Large-Eddy Simulation of the Stable Boundary Layer with Explicit Filtering and Reconstruction Turbulence Modeling
Large-eddy simulation (LES) of the stably stratified atmospheric boundary layer is performed using an explicit filtering and reconstruction approach with a finite difference method. Turbulent stresses are split into the resolvable subfilter-scale ...
Bowen Zhou; Fotini Katopodes Chow
Coexistence of Atmospheric Gravity Waves and Boundary Layer Rolls Observed by SAR
Both atmospheric gravity waves (AGW) and marine atmospheric boundary layer (MABL) rolls are simultaneously observed on an Environmental Satellite (Envisat) advanced synthetic aperture radar (ASAR) image acquired along the China coast on 22 May ...
Xiaofeng Li; Weizhong Zheng; Xiaofeng Yang; Jun A. Zhang; William G. Pichel; Ziwei Li
Boundary Layer Dynamics in a Simple Model for Convectively Coupled Gravity Waves
A simplified model of intermediate complexity for convectively coupled gravity waves that incorporates the bulk dynamics of the atmospheric boundary layer is developed and analyzed. The model comprises equations for velocity, potential ...
Michael L. Waite; Boualem Khouider
Acoustic Sounder Observations of the Atmospheric Boundary Layer from the Top of a Steep Mountain
Preliminary results from a series of experiments utilizing an acoustic sounder located at the top of a 1026 m mountain are presented which show some interesting features of the evolution of the atmospheric boundary layer.
D. N. Asimakopoulos; D. G. Deligiorgi; D. P. Lalas
Relevance of the Mesoscale Entrainment Instability to the Marine Cloud-topped Atmospheric Boundary Layer
Mesoscale variability in entrainment across the inversion capping the cloud-topped atmospheric boundary layer (CTBL) has been proposed as an explanation for mesoscale variability in cloud thickness. The relevance of this mechanism, called ...
Hugh A. Rand; Christopher S. Bretherton
The Development of a Scanning Raman Water Vapor Lidar for Boundary Layer and Tropospheric Observations
A scanning, ultraviolet, Raman water vapor lidar designed primarily for boundary layer measurements has been built and operated by the Los Alamos National Laboratory Ground-Based Earth Observing Network team. The system provides high temporal and ...
W. E. Eichinger; D. I. Cooper; P. R. Forman; J. Griegos; M. A. Osborn; D. Richter; L. L. Tellier; R. Thornton
Boundary Layer Height and Entrainment Zone Thickness Measured by Lidars and Wind-Profiling Radars
The authors examine measurements of boundary layer height zi and entrainment zone thickness observed with two lidars and with a radar wind profiler during the Flatland96 Lidars in Flat Terrain experiment. Lidar backscatter is proportional to ...
Stephen A. Cohn; Wayne M. Angevine
Aspects of Convective Boundary Layer Turbulence Measured by a Dual-Doppler Lidar System
Special designed dual-Doppler setups can be used to retrieve simultaneous measurements of two wind components with high temporal resolution in several heights throughout the atmospheric boundary layer. During a field campaign in summer 2011, ...
Luisa R�hner; Katja Tr�umner
This study demonstrates that a pulsed wind lidar is a reliable instrument for measuring angles between horizontal vectors of significance in the atmospheric boundary layer. Three different angles are considered: the wind turning, the angle between ...
Retrieval of Urban Boundary Layer Structures from Doppler Lidar Data. Part II: Proper Orthogonal Decomposition
The proper orthogonal decomposition technique is applied to 74 snapshots of 3D wind and temperature fields to study turbulent coherent structures and their interplay in the urban boundary layer over Oklahoma City, Oklahoma. These snapshots of ...
Ching-Long Lin; Quanxin Xia; Ronald Calhoun
Doppler Profiler and Radar Observations of Boundary Layer Variability during the Landfall of Tropical Storm Gabrielle
Detailed observations of boundary layer structure were acquired on 14 September 2001, prior to and during the landfall of Tropical Storm Gabrielle. The Mobile Integrated Profiling System (MIPS) and the Shared Mobile Atmospheric Research and ...
Kevin R. Knupp; Justin Walters; Michael Biggerstaff
A Coupled Hydrodynamic�Bottom Boundary Layer Model of Ekman Flow on Stratified Continental Shelves
This paper describes a hydrodynamic model with turbulent energy closure that uses a simplified wave-current interaction model of the bottom boundary layer to compute bed drag coefficients. The coupled model is used to investigate the interaction ...
Timothy R. Keen; Scott M. Glenn
The Role of Quantitative Infrared Imagery in Investigations of the Nocturnal Boundary Layer
During the Cooperative Atmospheric�Surface Exchange Study in 1999 (CASES99), an intensive investigation of the stable nocturnal boundary layer, a versatile and sensitive cryogenically cooled thermal imaging radiometer, the Inframetrics PM 380 ...
Lawrence F. Radke; Anthony C. Delany
Observational Evidence That Enhanced Subsidence Reduces Subtropical Marine Boundary Layer Cloudiness
Conventional wisdom suggests that subsidence favors the presence of marine stratus and stratocumulus because regions of enhanced boundary layer cloudiness are observed to climatologically co-occur with regions of enhanced subsidence. Here it is ...
Timothy A. Myers; Joel R. Norris
A new wall-shear stress model for atmospheric boundary layer simulations
A new wall-shear stress model to be used as wall-boundary condition for Large Eddy Simulations of the Atmospheric Boundary Layer is proposed. The new model computes the wall shear stress and the vertical derivatives of the streamwise velocity ...
Marcus Hultmark; Marc Calaf; Marc B. Parlange
Velocity and Stress in the Deep-Ocean Boundary Layer
In order to predict the response of deep ocean sediments to the near-bottom currents, accurate estimates of the near-bottom velocity and the boundary shear stress are necessary. Because of the unsteady nature of deep ocean currents, dynamic ...
S. R. McLean; J. Yean
Turbulent Mixing with Chemical Reaction in the Planetary Boundary Layer
Detailed statistics of the fluctuating concentration field produced by large-eddy simulations (LES) of the chemically reactive mixing of two species in a convectively driven mixed layer are presented. The effect of the turbulent mixing on the ...
R. I. Sykes; S. F. Parker; D. S. Henn; W. S. Lewellen
Mesoscale Modeling of Boundary Layer Refractivity and Atmospheric Ducting
In this study four mesoscale forecasting systems were used to investigate the four-dimensional structure of atmospheric refractivity and ducting layers that occur within evolving synoptic conditions over the eastern seaboard of the United States. ...
Tracy Haack; Changgui Wang; Sally Garrett; Anna Glazer; Jocelyn Mailhot; Robert Marshall
The Bottom Boundary Layer Over the Northern California Shelf
Moored temperature and shipboard CTD observations from a northern California coastal upwelling region reveal variable bottom mixed-layer heights that are typically 5�15 m, but occasionally exceed 50 m. Observations from Oregon, northern ...
Steven J. Lentz; John H. Trowbridge
Investigation of Upstream Boundary Layer Influence on Mountain Wave Breaking and Lee Wave Rotors Using a Large-Eddy Simulation
Interactions between a turbulent boundary layer and nonlinear mountain waves are explored using a large-eddy simulation model. Simulations of a self-induced critical layer, which develop a stagnation layer and a strong leeside surface jet, are ...
Craig M. Smith; Eric D. Skyllingstad
A Numerical Investigation of Tetroon versus Fluid Particle Dispersion in the Convective Planetary Boundary Layer
Data from Deardorff's (1974) turbulence model are used in simulations of fluid particle and tetroon dispersion in the convective atmospheric boundary layer with ?h/L ? 1, where h is the mixed-layer depth. It is found that the lateral spread ?y(t) ...
Robert G. Lamb
Convectivc Elements in the Marine Atmospheric Boundary Layer. Part II: Entrainment at the Capping Inversion
Data from two aircraft flights in the marine atmospheric boundary layer are analyzed in an investigation of entrainment processes at the top of the well-mixed layer. Both days had strong wind shear across the inversion, which is reflected in the ...
Role of Amorphous Boundary Layer in Enhancing Ionic Conductivity of Lithium�lanthanum�titanate Electrolyte
The low ionic conductivity is a bottleneck of the inorganic solid state electrolyte used for lithium ion battery. In ceramic electrolytes, grain boundary usually dominates the total conductivity. In order to improve the grain boundary effect, an amorphous silica layer is introduced into grain boundary of ceramic electrolytes based on lithium-lanthanum-titanate, as evidenced by electron microscopy. The results showed that the total ionic conductivity could be to be enhanced over 1 x 10{sup -4} S/cm at room temperature. The reasons can be attributed to removing the anisotropy of outer-shell of grains, supplement of lithium ions in various sites in grain boundary and close bindings among grains by the amorphous boundary layer among grains.
Mei, A.; Wang, X.; Lana, J.-L.; Fenga, Y.-C.; Genga, H.-X.; Lina, Y.-H.; Nana, C.-W.
On the Turbulent Mixing Length in the Oceanic Boundary Layer
Turbulence measurements from under drifting pack ice illustrate the distribution of turbulent mixing length in the well-mixed layer of the upper ocean. Mixing length (? ? K/u*, where K and u* are the local eddy viscosity and square root of ...
Miles G. Mcphee
Large-Eddy Simulations of Strongly Precipitating, Shallow, Stratocumulus-Topped Boundary Layers
Large-eddy simulations that incorporate a size-resolving representation of cloud water are used to study the effect of heavy drizzle on PBL structure. Simulated surface precipitation rates average about 1 mm day?1. Heavily drizzling simulations ...
Bjorn Stevens; William R. Cotton; Graham Feingold; Chin-Hoh Moeng
ARM - PI Product - Raman lidar/AERI PBL Height Product
ProductsRaman lidarAERI PBL Height Product Comments? We would love to hear from you Send us a note below or call us at 1-888-ARM-DATA. Send PI Product : Raman lidarAERI PBL...
The Boundary Layer of Mars: Fluxes, Stability, Turbulent Spectra, and Growth of the Mixed Layer
Spectra of wind from high-frequency measurements in the Martian atmospheric surface layer, along with the diurnal variation of the height of the mixed surface layer, are calculated for the first time for Mars. Heat and momentum fluxes, stability, ...
James E. Tillman; Lars Landberg; S�ren E. Larsen
Impact of Surface Flux Formulations and Geostrophic Forcing on Large-Eddy Simulations of Diurnal Atmospheric Boundary Layer Flow
The impact of surface flux boundary conditions and geostrophic forcing on multiday evolution of flow in the atmospheric boundary layer (ABL) was assessed using large-eddy simulations (LES). The LES investigations included several combinations of ...
Vijayant Kumar; Gunilla Svensson; A. A. M. Holtslag; Charles Meneveau; Marc B. Parlange
Comparison of two-equation turbulence models for boundary layers with pressure gradient
This paper compares the performance of eight low Reynolds number k-epsilon and k-omega models for high Reynolds number, incompressible turbulent boundary layers with favorable, zero, and adverse pressure gradients. Results obtained underscore the k-epsilon model's unsuitability for such flows. Even more seriously, the k-epsilon model is demonstrated to be inconsistent with the well-established physical structure of the turbulent boundary layer, and low Reynolds number corrections cannot remove the inconsistency. By contrast, the k-omega model, with and without low Reynolds number modifications, proves to be very accurate for all of the tests conducted. 16 refs.
Wilcox, D.C. (DCW Industries, Inc., La Canada, CA (United States))
Anthropogenic moisture production and its effect on boundary layer circulations over New York City
A heat and moisture excess over New York City is shown to exist by the analysis of helicopter soundings of temperature and wet bulb depression. The magnitude of the temporal and spatial distribution of anthropogenic moisture emissions in New York City were estimated from fuel usage data. The URBMET urban boundary layer model was used to evaluate the effects on the dynamics of the urban boundary layer resulting from the observed urban moisture excess. Work is currently in progress which seeks to determine the fraction of the observed moisture excess over New York that is due to anthropogenic sources. (auth)
Bornstein, R.D.; Tam, Y.T.
The effect of periodic unsteady wakes on boundary layer transition and heat transfer on a curved plate.
??The effect of unsteady periodic wakes on heat transfer and boundary layer transition was investigated on a constant curvature heat transfer curved plate in a� (more)
Wright, Lance Cole
Rolls, Streets, Waves, and More: A Review of Quasi-Two-Dimensional Structures in the Atmospheric Boundary Layer
The atmospheric boundary layer is home to a number of horizontally elongated quasi-two-dimensionalphenomena including cloud streets, roll vortices, thermal waves, and surface layer streaks. These phenomena, their dynamics, and their interactions ...
George S. Young; David A. R. Kristovich; Mark R. Hjelmfelt; Ralph C. Foster
Observations of the Interaction between Cumulus Clouds and Warm Stratocumulus Clouds in the Marine Boundary Layer during ASTEX
Decoupling of the marine boundary layer beneath stratocumulus clouds and the formation of cumulus clouds at the top of a surface-based mixed layer (SML) have frequently been observed and modeled. When such cumulus clouds penetrate the overlying ...
G. M. Martin; D. W. Johnson; D. P. Rogers; P. R. Jonas; P. Minnis; D. A. Hegg
Turbulence Structure of the Convective Boundary Layer. Part II. Phonenix 78 Aircraft Observations of Thermals and Their Environment
A conditional sampling technique based upon the mixed layer spectra of vertical velocity and temperature is developed. This technique is used to analyze the turbulence data obtained by aircraft during the Phoenix 78 convective boundary layer ...
George S. Young
An experimental and numerical study of boundary layer structure over areas of inhomogeneous sensible heat fluxes
In June of 1992 a boundary-layer experiment was carried out near Boardman, Oregon. The campaigns were part of a program of studies under the auspices of the US Department of Energy`s Atmospheric Radiation Measurement (ARM) program, whose goal is to improve the treatment of radiative transfer, particularly as affected by clouds, in general circulation models (GCMs) used for climate studies. One aspect of this program is concerned with the determination of appropriate lower boundary conditions for such models and the representation of subgrid-scale variability in regions where the surface conditions are not uniform. To study this problem, boundary-layer and surface properties were measured over a region of two sharply contrasting land types: a large, dry, sagebrush steppe area and irrigated farmland that formed the east, northeast, and western borders of the steppe. A combination of surface flux instrumentation, airsondes, sodars, and near-surface wind and temperature sensors was used. Measurements were carried out over the eastern portion of this region, which featured a well-defined boundary between the dry and irrigated areas. In this paper, the authors present some results from those observations and from a set of numerical simulations that address the effects of inhomogeneous surface fluxes on boundary-layer structure.
Zhong, S.; Doran, J.C.
A Mean-Gradient Model of the Dry Convective Boundary Layer
A mean-gradient model of the dry convective boundary layer is developed using a convective mass flux representation of the turbulent fluxes. A top-hat model of thermals is used to represent the average characteristics of updrafts and downdrafts ...
Shouping Wang; Bruce A. Albrecht
Observations of the Nocturnal Boundary Layer Associated with the West African Monsoon
A set of nighttime tethered balloon and kite measurements from the central Sahel (15.2�N, 1.3�W) in August 2005 were acquired and analyzed. A composite of all the nights� data was produced using boundary layer height to normalize measured ...
Caroline L. Bain; Douglas J. Parker; Christopher M. Taylor; Laurent Kergoat; Fran�oise Guichard
Mechanisms for Diurnal Boundary Layer Circulations in the Great Basin Desert
The purpose of this observation- and model-based study of the Great Basin Desert boundary layer is to illustrate the variety of locally forced circulations that can affect such an area during a diurnal cycle. The area of the Great Basin Desert (...
Daran L. Rife; Thomas T. Warner; Fei Chen; Elford G. Astling
An overview on the Urban Boundary-layer Atmosphere Network in Helsinki
Helsinki UrBAN (Urban Boundary-layer Atmosphere Network, http://urban.fmi.fi) is a dedicated research-grade observational network where we study the physical processes in the atmosphere above the city. Helsinki UrBAN is the most poleward intensive urban ...
Wood CR; J�rvi L; Kouznetsov RD; Nordbo A; Joffre S; Drebs A; Vihma T; Hirsikko A; Suomi I; Fortelius C; O'Connor E; Moiseev D; Haapanala S; Moilanen J; Kangas M; Karppinen A; Vesala T; Kukkonen J
Revisiting the Definition of the Drag Coefficient in the Marine Atmospheric Boundary Layer
A new functional form of the neutral drag coefficient for moderate to high wind speeds in the marine atmospheric boundary layer for a range of field measurements as reported in the literature is proposed. This new form is found to describe a wide ...
Richard J. Foreman; Stefan Emeis
Large-Eddy Simulations and Observations of Atmospheric Marine Boundary Layers above Nonequilibrium Surface Waves
Winds and waves in marine boundary layers are often in an unsettled state when fast-running swell generated by distant storms propagates into local regions and modifies the overlying turbulent fields. A large-eddy simulation (LES) model with the ...
Peter P. Sullivan; James B. Edson; Tihomir Hristov; James C. McWilliams
Lidar Investigation of Tropical Nocturnal Boundary Layer Aerosols and Cloud Macrophysics
Observational evidence of two-way association between nocturnal boundary layer aerosols and cloud macrophysical properties under different meteorological conditions is reported in this paper. The study has been conducted during 2008-09 employing a high space-time resolution polarimetric micro-pulse lidar over a tropical urban station in India. Firstly, the study highlights the crucial role of boundary layer aerosols and background meteorology on the formation and structure of low-level stratiform clouds in the backdrop of different atmospheric stability conditions. Turbulent mixing induced by the wind shear at the station, which is associated with a complex terrain, is found to play a pivotal role in the formation and structural evolution of nocturnal boundary layer clouds. Secondly, it is shown that the trapping of energy in the form of outgoing terrestrial radiation by the overlying low-level clouds can enhance the aerosol mixing height associated with the nocturnal boundary layer. To substantiate this, the long-wave heating associated with cloud capping has been quantitatively estimated in an indirect way by employing an Advanced Research Weather Research and Forecasting (WRF-ARW) model version 2.2 developed by National Center for Atmospheric Research (NCAR), Colorado, USA, and supplementary data sets; and differentiated against other heating mechanisms. The present investigation as well establishes the potential of lidar remote-sensing technique in exploring some of the intriguing aspects of the cloud-environment relationship.
Manoj, M. G.; Devara, PC S.; Taraphdar, Sourav
The Structure of a Fair Weather Boundary Layer Based on the Results of Several Measurement Strategies
A fair weather boundary layer (BL) with light winds and scattered cumulus to 1100 m is examined in the GATE C-scale triangle using data from tethered balloons, surface measurements from the booms of the ships, structure sondes and gust probe ...
Gary Barnes; George D. Emmitt; Burghard Brummer; Margaret A. LeMone; Stephen Nicholls
Can an E�l Turbulence Closure Simulate Entrainment in Radiatively Driven Convective Boundary Layers?
The simulation of entrainment by an (E�l) turbulent kinetic energy�diagnostic length scale closure model is investigated in a smoke cloud convective boundary layer. The behavior of the E�l scheme is compared with two simple entrainment closures ...
Geert Lenderink; Margreet C. vanZanten; Peter G. Duynkerke
On the Structure of Turbulence in the Bottom Boundary Layer of the Coastal Ocean
Six sets of particle image velocimetry (PIV) data from the bottom boundary layer of the coastal ocean are examined. The data represent periods when the mean currents are higher, of the same order, and much weaker than the wave-induced motions. ...
W. A. M. Nimmo Smith; J. Katz; T. R. Osborn
Numerical Simulations of the Marine Stratocumulus-Capped Boundary Layer and Its Diurnal Variation
A high-resolution one-dimensional version of a second-order turbulence radiative�convective model, developed at Los Alamos National Laboratory, is used to simulate the diurnal cycle of the marine stratocumulus cloud-capped boundary layer. The ...
W. S. Smith; C-Y. J. Kao
Stable Boundary Layer Depth from High-Resolution Measurements of the Mean Wind Profile
The depth h of the stable boundary layer (SBL) has long been an elusive measurement. In this diagnostic study the use of high-quality, high-resolution (?z = 10 m) vertical profile data of the mean wind U(z) and streamwise variance ?u2(z) is ...
Yelena L. Pichugina; Robert M. Banta
The Very Stable Boundary Layer on Nights with Weak Low-Level Jets
The light-wind, clear-sky, very stable boundary layer (vSBL) is characterized by large values of bulk Richardson number. The light winds produce weak shear, turbulence, and mixing, and resulting strong temperature gradients near the surface. Here ...
Robert M. Banta; Larry Mahrt; Dean Vickers; Jielun Sun; Ben B. Balsley; Yelena L. Pichugina; Eric J. Williams
A Model for Objective Simulation of Boundary-Layer Winds in an Area of Complex Terrain
An objective analysis model is formulated to simulate the boundary-layer wind field in an area of complex terrain on the island of Oahu, Hawaii. The model is designed to reproduce the effects of the terrain on the undisturbed trade wind flow in ...
D. Andr� Erasmus
A six-year climatology of fronts affecting Helsinki, Finland and their boundary layer structure
A six-year climatology of the frequency, characteristics, and boundary-layer structure of synoptic-scale fronts in Helsinki, Finland was created using significant weather charts and observations from a 327 m tall mast and from the Station for ...
Doppler Radar Observations of the Development of a Boundary-Layer Nocturnal Jet
A single Doppler radar obtained detailed clear-air measurements of the development of a strong boundary-layer nocturnal jet in North Dakota during the summer of 1989. The evolution of the jet was monitored by the radar with a high degree of ...
A. Shelby Frisch; Brad W. Orr; Brooks E. Martner
Very simple, carbuncle-free, boundary-layer-resolving, rotated-hybrid Riemann solvers
In this paper, we propose new Euler flux functions for use in a finite-volume Euler/Navier-Stokes code, which are very simple, carbuncle-free, yet have an excellent boundary-layer-resolving capability, by combining two different Riemann solvers into ... Keywords: Carbuncle, Hybrid schemes, Rotated Riemann solvers, Shock instability, Upwind schemes
Hiroaki Nishikawa; Keiichi Kitamura
Bulk Models of the Sheared Convective Boundary Layer: Evaluation through Large Eddy Simulations
A set of first-order model (FOM) equations, describing the sheared convective boundary layer (CBL) evolution, is derived. The model output is compared with predictions of the zero-order bulk model (ZOM) for the same CBL type. Large eddy ...
Robert Conzemius; Evgeni Fedorovich
An Integrated Turbulence Scheme for Boundary Layers with Shallow Cumulus Applied to Pollutant Transport
A scheme is described that provides an integrated description of turbulent transport in free convective boundary layers with shallow cumulus. The scheme uses a mass-flux formulation, as is commonly found in cumulus schemes, and a 1.5-order ...
Wayne M. Angevine
Performance of an Eddy Diffusivity�Mass Flux Scheme for Shallow Cumulus Boundary Layers
Comparisons between single-column (SCM) simulations with the total energy�mass flux boundary layer scheme (TEMF) and large-eddy simulations (LES) are shown for four cases from the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) ...
Wayne M. Angevine; Hongli Jiang; Thorsten Mauritsen
The Minimum Wind Speed for Sustainable Turbulence in the Nocturnal Boundary Layer
The collapse of turbulence in the nocturnal boundary layer is studied by means of a simple bulk model that describes the basic physical interactions in the surface energy balance. It is shown that for a given mechanical forcing, the amount of ...
B. J. H. Van de Wiel; A. F. Moene; H. J. J. Jonker; P. Baas; S. Basu; J. M. M. Donda; J. Sun; A. A. M. Holtslag
The Coastal Bottom Boundary Layer: A Note on the Model of Chapman and Lentz
The bottom boundary layer of a stratified flow on a coastal continental shelf is examined using the model of Chapman and Lentz. The flow is driven by a surface stress, uniform in the alongshore coordinate, in a downwelling-favorable direction. ...
Joseph Pedlosky
Trapping of a Coastal Density Front by the Bottom Boundary Layer
The dynamics of a surface-to-bottom density front on a uniformly sloping continental shelf and the role of density advection in the bottom boundary layer are examined using a three-dimensional, primitive equation numerical model. The front is ...
David C. Chapman; Steven J. Lentz
The IMADA-AVER Boundary Layer Experiment in the Mexico City Area
A boundary layer field experiment in the Mexico City basin during the period 24 February�22 March 1997 is described. A total of six sites were instrumented. At four of the sites, 915-MHz radar wind profilers were deployed and radiosondes were ...
J. C. Doran; X. Bian; S. F. J. de Wekker; S. Edgerton; J. D. Fast; J. M. Hubbe; W. J. Shaw; C. D. Whiteman; S. Abbott; C. King; J. Leach; M. Mulhearn; C. Russell; B. Templeman; D. Wolfe; J. Archuleta; S. Elliott; A. Fernandez; D. Langley; J. T. Lee; W. Porch; L. Tellier; J. Chow; J. G. Watson; R. L. Coulter; T. J. Martin; J. D. Shannon; R. White; D. Martinez; J. L. Martinez; V. Mora; G. Sosa; G. Mercado; J. L. Pena; R. Salas; R. Petty
The Vertical Distribution of Radon in Clear and Cloudy Daytime Terrestrial Boundary Layers
Radon (222Rn) is a powerful natural tracer of mixing and exchange processes in the atmospheric boundary layer. The authors present and discuss the main features of a unique dataset of 50 high-resolution vertical radon profiles up to 3500 m above ...
Alastair G. Williams; Wlodek Zahorowski; Scott Chambers; Alan Griffiths; J�rg M. Hacker; Adrian Element; Sylvester Werczynski
Comparative Evaluation of Eddy Exchange Coefficients for Strong and Weak Wind Stable Boundary Layer Modeling
Five local K-closure formulations and a TKE closure were incorporated in a one-dimensional version of the Pielke�s model, and a comparative evaluation of the closure schemes was made for strong and weak wind stable boundary layer (SBL). The ...
Maithili Sharan; S. G. Gopalakrishnan
Transport and Resuspension of Fine Particles in a Tidal Boundary Layer near a Small Peninsula
The authors present a theory on the transport and resuspension of fine particles in a tidal boundary layer when the ambient tidal flow is nonuniform due to a peninsula along the coastline. As a first step toward better physical understanding the ...
Chiang C. Mei; Chimin Chian; Feng Ye
Cyclonic Spirals in Tidally Accelerating Bottom Boundary Layers in the Zhujiang (Pearl River) Estuary
A velocity spiral in the tidally accelerating bottom boundary layer (BBL) was defined as a directional shear of the prevailing flow with the elevation and the tidal phase. However, so far there is no information on the spiral for the oscillatory ...
Jiaxue Wu; Huan Liu; Jie Ren; Junjie Deng
Measurement of Turbulence in the Oceanic Bottom Boundary layer with an Acoustic Current Meter Array
A vertical array of acoustic current meters measures the vector flow field in the lowest 5 m of the oceanic boundary layer. By resolving the velocity to 0.03 cm s?1 over 15 cm paths, it samples the dominant turbulent eddies responsible for ...
Albert J. Williams 3rd; John S. Tochko; Richard L. Koehler; William D. Grant; Thomas F. Gross; Christopher V. R. Dunn
Effect of wave boundary layer on sea-to-air dimethylsulfide transfer velocity during typhoon passage
: Dimethylsulfide; Sea-to-air gas transfer velocity; Wave boundary layer; Tropical cyclone; Drag coefficient in order to accurately calculate aerosol radiative forcing. The sea-to-air DMS flux depends on airside coefficient CD and roughness length z0 has been investigated over small areas of the sea or in wave tanks
Chu, Peter C.
The Three-Dimensional Structure and Evolution of a Tornado Boundary Layer
The finescale three-dimensional structure and evolution of the near-surface boundary layer of a tornado (TBL) is mapped for the first time. The multibeam Rapid-Scan Doppler on Wheels (RSDOW) collected data at several vertical levels, as low as 4, ...
Karen A. Kosiba; Joshua Wurman
Local Versus Nonlocal Boundary-Layer Diffusion in a Global Climate Model
The results of a local and a nonlocal scheme for vertical diffusion in the atmospheric boundary layer are compared within the context of a global climate model. The global model is an updated version of the NCAR Community Climate Model (CCM2). ...
A. A. M. Holtslag; B. A. Boville
Observed Characteristics of the Afternoon�Evening Boundary Layer Transition Based on Sodar and Surface Data
The early-evening boundary layer transition has been defined in the past using a variety of criteria, the most popular of which is the onset of a negative surface heat flux. According to this definition, the transition is an almost-instantaneous ...
Jessica Busse; Kevin Knupp
Stable Atmospheric Boundary Layers and Diurnal Cycles: Challenges for Weather and Climate Models
The representation of the atmospheric boundary layer is an important part of weather and climate models and impacts many applications such as air quality and wind energy. Over the years, the performance in modeling 2-m temperature and 10-m wind speed has ...
A. A. M. Holtslag; G. Svensson; P. Baas; S. Basu; B. Beare; A. C. M. Beljaars; F. C. Bosveld; J. Cuxart; J. Lindvall; G. J. Steeneveld; M. Tjernstr�m; B. J. H. Van De Wiel
An Overview of the Urban Boundary Layer Atmosphere Network in Helsinki
The Helsinki Urban Boundary-Layer Atmosphere Network (UrBAN: http://urban.fmi.fi) is a dedicated research-grade observational network where the physical processes in the atmosphere above the city are studied. Helsinki UrBAN is the most poleward intensive ...
C. R. Wood; L. J�rvi; R. D. Kouznetsov; A. Nordbo; S. Joffre; A. Drebs; T. Vihma; A. Hirsikko; I. Suomi; C. Fortelius; E. O'Connor; D. Moiseev; S. Haapanala; J. Moilanen; M. Kangas; A. Karppinen; T. Vesala; J. Kukkonen
A PDF-Based Model for Boundary Layer Clouds. Part I: Method and Model Description
A new cloudy boundary layer single-column model is presented. It is designed to be flexible enough to represent a variety of cloudiness regimes�such as cumulus, stratocumulus, and clear regimes�without the need for case-specific adjustments. The ...
Jean-Christophe Golaz; Vincent E. Larson; William R. Cotton
A PDF-Based Model for Boundary Layer Clouds. Part II: Model Results
A new single-column model for the cloudy boundary layer, described in a companion paper, is tested for a variety of regimes. To represent the subgrid-scale variability, the model uses a joint probability density function (PDF) of vertical ...
Sea-Breeze Circulation over Jakarta, Indonesia: A Climatology Based on Boundary Layer Radar Observations
Characteristics of sea-breeze circulation over the tropical site of Jakarta, Indonesia, have been documented based on analyses of satellite images and data from long-term L-band boundary layer radar measurements carried out at Serpong (6.4�S, ...
Tri W. Hadi; T. Horinouchi; T. Tsuda; H. Hashiguchi; S. Fukao
Horizontal Roll and Boundary-Layer Interrelationships Observed over Lake Michigan
On 7, 9 and 10 January 1981 some 35 hours of organized horizontal roll convection in the boundary layer over lake Michigan were probed with two airplanes and two radars from the University of Chicago Lake Snow Project. During this time, roll ...
Robert D. Kelly
Boundary-Layer Structure Over Tropical Oceans from TIROS-N Infrared Sounder Observations
It has been shown by simulation studies that the 13.4, 11.1 and 8.3 ?m spectral radiances are sensitive to the moisture distribution within the boundary layer. If the distribution gets significantly perturbed due to some stratification present in ...
Vijay K. Agarwal; A. V. Ashajayanthi
The Amazon Boundary-Layer Experiment (ABLE 2B): A Meteorological Perspective
In July and August 1985, and April and May 1987, two atmospheric chemistry field experiments called the Amazon Boundary-layer Experiments, (ABLE 2A and 2B) were conducted from a base near Manaus, Brazil in the central Amazon basin. The ...
Michael Garstang; Steven Greco; John Scala; Robert Swap; Stanley Ulanski; David Fitzjarrald; David Martin; Edward Browell; Mark Shipman; Vickie Connors; Robert Harriss; Robert Talbot
Posters Triggering of Boundary Layer Cumulus Clouds Over a Heterogeneous Surface
5 5 Posters Triggering of Boundary Layer Cumulus Clouds Over a Heterogeneous Surface K. Schrieber, R. Stull, and Q. Zhang Boundary Layer Research Team Department of Atmospheric and Oceanic Science University of Wisconsin Madison, Wisconsin Complex multimodal joint frequency distributions of LCL height versus θ v in surface-layer air over a large heteroge- neous surface area are modeled as the superposition of simpler mono-modal distributions. These simpler distri- butions, which apply to quasi-homogeneous subdomains, are approximated with bivariate distribution models. The shape of each of these modeled distributions depends on variations of the Bowen ratio and heat input forcings. These forcings are a function of the landscape, insolation, surface albedo, cloud-shading, soil moisture, and other
Modeling the Evolution of the Atmospheric Boundary Layer Coupled to the Land Surface for Three Contrasting Nights in CASES-99
The modeling and prediction of the stable boundary layer over land is a persistent, problematic feature in weather, climate, and air quality topics. Here, the performance of a state-of-the-art single-column boundary layer model is evaluated with ...
G. J. Steeneveld; B. J. H. van de Wiel; A. A. M. Holtslag
Evaluating the Performance of Planetary Boundary Layer and Cloud Microphysical Parameterization Schemes in Convection-Permitting Ensemble Forecasts using
uncertainty in how to include various processes (e.g., drop breakup and ice-phase categories 1 Evaluating the Performance of Planetary Boundary Layer and Cloud Microphysical Parameterization In this study, the ability of several cloud microphysical and planetary boundary layer parameterization schemes
Xue, Ming
Climatology of a Summer Coastal Boundary Layer with 1290-MHz Wind Profiler Radar and a WRF Simulation
A study of the Israeli summer coastal boundary layer (BL) with a 1290-MHz wind profiler located 3.5 km from the coastline has revealed four main features associated with the sea-breeze onset: 1) by midday the boundary layer height drops by an ...
Yoav Levi; Elad Shilo; Ilan Setter
Non-local closure model for vertical mixing in the convective boundary layer
A simple non-local closure model for vertical mixing in Convective Boundary Layers (CBL) has been developed specifically for application in regional or meso-scale atmospheric chemistry models. The model, named the Asymmetrical Convective Model (ACM), is based on the concept that vertical transport within the CBL is inherently asymmetrical. Upward transport by buoyant plumes originating in the surface layer is simulated by mixing from the lowest model layer directly to all other layers in the CBL. Downward transport, however, proceeds only to the next lower layer in order to emulate gradual compensatory subsidence. The realism of the ACM is tested through comparisons to large-eddy simulations of several idealized test cases. The ACM is also tested in the context of the Regional Acid Deposition Model (RADM) both to determine sensitivity to different CBL mixing schemes and to compare to vertically resolved aircraft measurements. These tests demonstrate quicker upward transport of ground level emissions by the ACM as compared to the eddy diffusion scheme currently used in RADM. The ACM also affects ozone photochemistry in the boundary layer resulting in lower ozone concentrations in areas of high NOx emissions.
Pleim, J.E.; Chang, J.S.
Four-Dimensional Data Assimilation Boundary-Layer Observations Over the Southern
Boundary-Layer Observations Over the Southern Boundary-Layer Observations Over the Southern Great Plains Cloud and Radiation Testbed Site During the November Flux-Profiler Test s. P. Oncley and J. Van Baelen National Center for Atmospheric Research(8) Boulder, CO 80307-3000 Introduction Resu Its Figure 1 shows the raw data from two of the ten profile patterns flown during this experiment. Each aircraft profile consisted of a descent to the profiler site followed by 3-5 legs at increasing heights. Note that because of this flightpattern, the downward and upward profiles may differ due to temporal changes during the time of the pattern (about 50 minutes) and due to horizontal gradients. The profiler was operated in DBS mode alternating between two sets of three beams. Thus, two sets of consensus- averaged winds were available. Finally, several
An experimental and numerical study of the modifications of mixed-layer structure by inhomogeneous surface fluxes and secondary circulations
The problem of scale interactions in the planetary boundary layer (PBL), i.e., how forcing mechanisms of differing spatial and temporal scales affect the properties of the PBL, has been a subject of considerable interest for some time. One aspect of this problem that has received increasing attention in recent years is the representation, in mesoscale and general circulation models. of the effects of subgrid-scale inhomogeneities in surface properties. Differences in sensible and latent heat fluxes between adjacent areas can result in secondary circulations. modifications to the boundary layer structure, and the transport of heat and moisture from one area to another. Despite their potential included on local PBL properties, such effects can not be resolved by numerical models whose scale is too coarse; thus, suitable parameterizations that account for these phenomena are needed. In this paper the authors present some results of wind and temperature measurements over an area with significant variations in surface fluxes on scales of O(10 km). They then use fine resolution numerical simulations to show how synoptic, topographical, and thermal forcing combine to affect the properties of the PBL in the region. Specifically, they consider the relative importance of topography and land-use differences on the generation of secondary circulations and on the depth of the mixed layer, and they show how these effects are modified by synoptic wind fields. Implications for coarser resolution models are also discussed.
Numerical study of boundary layer injection as a scale control method
A boundary layer injection method of controlling scale-buildup in geothermal two-phase flow nozzles is studied. The object of this study is to set an upper limit on the ratio of the injected mass flow rate to the free stream mass flow rate that is necessary to isolate the scale carrying free stream flow from the nozzle wall. In order to develop a numerical model of the boundary layer flow, assumptions are made which reduce the results to order of magnitude approximations. Two configurations of nozzles with various injection flow rates are tried. It is found by numerical experiment that a nozzle with injection through a 1 mm thick ring near the inlet, is more efficient at isolating the free stream than a porous nozzle. A mass flow rate ratio of 0.173% was necessary to achieve this effect. It may be concluded that an upper limit on the mass flow rate ratio is about 2.0% with injection through a ring near the inlet, and that boundary layer injection is a reasonable method of controlling scale-buildup. A glossary of variables, program documentation and listings are presented for programs GMD15SR8, TRACK11, and TRACK12.
Feiereisen, W.
Numerical and Laboratory Study of a Horizontally Evolving Convective Boundary Layer. Part I: Transition Regimes and Development of the Mixed Layer
Results are presented from a large eddy simulation (LES) and wind tunnel study of the turbulence regime in a horizontally evolving sheared atmospheric convective boundary layer (CBL) capped by a temperature inversion. The wind tunnel part of the ...
E. Fedorovich; F. T. M. Nieuwstadt; R. Kaiser
Observations of the Evolution of the Nocturnal and Convective Boundary Layers and the Structure of Open-Celled Convection on 14 June 2002
The Boundary Layer Evolution (BLE) missions of the International H2O Project (IHOP_2002) were designed to provide comprehensive observations of the distribution of water vapor in the quiescent boundary layer and its evolution during the early ...
Lindsay J. Bennett; Tammy M. Weckwerth; Alan M. Blyth; Bart Geerts; Qun Miao; Yvette P. Richardson
Evolution of the lower planetary boundary layer over strongly contrasting surfaces
In a multilaboratory field study held near Boardman in northeastern Oregon in June 1991, various properties of the surface and lower atmospheric boundary layer over heavily irrigated cropland and adjacent desert steppe were investigated in the initial campaign of the Atmospheric Radiation Measurement (ARM) program. The locale was selected because its disparate characteristics over various spatial scales stress the ability of general circulation models (GCMS) to describe lower boundary conditions, particularly across the discontinuity between desert (in which turbulent flux of heat must be primarily as sensible heat) and large irrigated tracts (in which turbulent flux of latent heat should be the larger term). This campaign of ARM seeks to increase knowledge in three critical areas: (1) determination of the relationships between surface heat fluxes measured over multiple scales and the controlling surface parameters within each scale, (2) integration of local and nearly local heat flux estimates to produce estimates appropriate for GCM grid cells of 100-200 km horizontal dimension, and (3) characterization of the growth and development of the atmospheric boundary layer near transitions between surfaces with strongly contrasting moisture availabilities.
Coulter, R.L.; Gao, W.; Martin, T.J.; Shannon, J.D. [Argonne National Lab., IL (United States); Doran, J.C.; Hubbe, J.M.; Shaw, W.M. [Pacific Northwest Lab., Richland, WA (United States)
Coulter, R.L.; Gao, W.; Martin, T.J.; Shannon, J.D. (Argonne National Lab., IL (United States)); Doran, J.C.; Hubbe, J.M.; Shaw, W.M. (Pacific Northwest Lab., Richland, WA (United States))
The Vertical Structure of the Wave Bottom Boundary Layer over a Sloping Bed: Theory and Field Measurements
Theoretical solutions for the wave bottom boundary layer (WBL) over a sloping bed are compared with field measurements in the nearshore zone. The WBL theory is constructed using both viscoelastic�diffusion and conventional eddy viscosity ...
Qingping Zou; Alex E. Hay
Air�Sea Exchange in Hurricanes: Synthesis of Observations from the Coupled Boundary Layer Air�Sea Transfer Experiment
The Coupled Boundary Layer Air�Sea Transfer (CBLAST) field program, conducted from 2002 to 2004, has provided a wealth of new air�sea interaction observations in hurricanes. The wind speed range for which turbulent momentum and moisture exchange ...
Peter G. Black; Eric A. D'Asaro; Thomas B. Sanford; William M. Drennan; Jun A. Zhang; Jeffrey R. French; Pearn P. Niiler; Eric J. Terrill; Edward J. Walsh
Response of an Oceanic Bottom Boundary Layer on a Slope to Interior Flow. Part I: Time-Independent Interior Flow
The behavior of oceanic boundary layers on a sloping bottom in the presence of stratification is investigated by the method of direct numerical simulations. The Navier�Stokes equations are decomposed into mean and turbulent components with the ...
Dave Ramsden
Turbulent Velocity-Variance Profiles in the Stable Boundary Layer Generated by a Nocturnal Low-Level Jet
Profiles of mean winds and turbulence were measured by the High Resolution Doppler lidar in the strong-wind stable boundary layer (SBL) with continuous turbulence. The turbulence quantity measured was the variance of the streamwise wind velocity ...
Robert M. Banta; Yelena L. Pichugina; W. Alan Brewer
Research Radar Analyses of the Internal Boundary Layer over Cape Canaveral, Florida, during the Landfall of Hurricane Frances (2004)
The structure of the coastal internal boundary layer (IBL) during a landfalling hurricane has important ramifications on operational forecasting, structural design, and poststorm damage assessment. Despite these important issues, the mean IBL ...
Brian D. Hirth; John L. Schroeder; Christopher C. Weiss; Douglas A. Smith; Michael I. Biggerstaff
Importance of Accurate Liquid Water Path for Estimation of Solar Radiation in Warm Boundary Layer Clouds: An Observational Study
A 1-yr observational study of overcast boundary layer stratus at the U.S. Department of Energy Atmospheric Radiation Measurement Program Southern Great Plains site illustrates that surface radiation has a higher sensitivity to cloud liquid water ...
Manajit Sengupta; Eugene E. Clothiaux; Thomas P. Ackerman; Seiji Kato; Qilong Min
Sensitivity of Climate Simulations to Land-Surface and Atmospheric Boundary-Layer Treatments-A Review
Aspects of the land-surface and boundary-layer treatments in some 20 or so atmospheric general circulation models (GCMS) are summarized. In only a small fraction of these have significant sensitivity studies been carried out and published. ...
J. R. Garratt
Wind Tunnel Study of Turbulent Flow Structure in the Convective Boundary Layer Capped by a Temperature Inversion
Experiments on simulating the atmospheric convective boundary layer (CBL), capped by a temperature inversion and affected by surface shear, were carried out in the thermally stratified wind tunnel of the Institute of Hydrology and Water Resources,...
Evgeni Fedorovich; Rolf Kaiser; Matthias Rau; Erich Plate
Spatial and Temporal Scales of Boundary Layer Wind Predictability in Response to Small-Amplitude Land Surface Uncertainty
Predictability experiments with the Weather Research and Forecast (WRF) model as a proxy for the atmosphere are analyzed to quantify the spatial and temporal scales of boundary layer wind response to land surface perturbations. Soil moisture is ...
Joshua P. Hacker
Grid Adaption and Its Effect on Entrainment in an E�l Model of the Atmospheric Boundary Layer
A one-dimensional numerical model KOLUM is introduced that demonstrates the use of continuous dynamic grid adaption in modeling the atmospheric boundary layer. The entrainment rates of KOLUM are compared against recent calibrations for smoke ...
Brian H. Fiedler
Modeling the Trade-Wind Cumulus Boundary Layer. Part I: Testing the Ensemble Cloud Relations Against Numerical Data
The possibility of studying the cloudy planetary boundary layer through one-dimensional modeling is investigated. The various possible parameterizations of mean liquid water content and correlations, in term of the known statistical properties of ...
Ph Bougeault
Comparative Experiments with MAPS on Different Parameterization Schemes for Surface Moisture Flux and Boundary-Layer Processes
This study compares several formulations parameterizing the surface moisture flux and boundary-layer processes using the ?-? hybrid-b model of the Mesoscale Analysis and Prediction System (MAPS) within both 1D and 3D frameworks.
Zaitao Pan; Stanley G. Benjamin; John M. Brown; Tatiana Smirnova
Distribution of Energy Spectra, Reynolds Stresses, Turbulence Production, and Dissipation in a Tidally Driven Bottom Boundary Layer
Seven sets of 2D particle image velocimetry data obtained in the bottom boundary layer of the coastal ocean along the South Carolina and Georgia coast [at the South Atlantic Bight Synoptic Offshore Observational Network (SABSOON) site] are ...
L. Luznik; W. Zhu; R. Gurka; J. Katz; W. A. M. Nimmo Smith; T. R. Osborn
An Observational and Modeling Study of Characteristics of Urban Heat Island and Boundary Layer Structures in Beijing
In this paper, the characteristics of urban heat island (UHI) and boundary layer structures in the Beijing area, China, are analyzed using conventional and Moderate Resolution Imaging Spectroradiometer (MODIS) observations. The Weather Research ...
Shiguang Miao; Fei Chen; Margaret A. LeMone; Mukul Tewari; Qingchun Li; Yingchun Wang
The Interaction between an Internal Gravity Wave and Turbulence in the Stably-Stratified Nocturnal Boundary Layer
Observations have been made of a stably-stratified nighttime boundary layer perturbed by Kelvin-Helmholtz internal waves with critical levels around 600 m. Significant turbulence intensities were measured although the time-mean gradient ...
J. J. Finnigan; F. Einaudi; D. Fua
Evaluation of an LES-Based Wind Profiler Simulator for Observations of a Daytime Atmospheric Convective Boundary Layer
The daytime atmospheric convective boundary layer (CBL) is characterized by strong turbulence that is primarily caused by buoyancy forced from the heated underlying surface. The present study considers a combination of a virtual radar and large ...
Danny E. Scipi�n; Phillip B. Chilson; Evgeni Fedorovich; Robert D. Palmer
A Finite-Element Model of the Atmospheric Boundary Layer Suitable for Use with Numerical Weather Prediction Models
We give a detailed description of an atmospheric boundary layer model capable of simulating the diurnal cycles of wind, temperature and humidity. The model includes a formulation of various physical processes (radiative effects, variation of soil ...
J. Mailhot; R. Benoit
The Effect of Mesh Resolution on Convective Boundary Layer Statistics and Structures Generated by Large-Eddy Simulation
A massively parallel large-eddy simulation (LES) code for planetary boundary layers (PBLs) that utilizes pseudospectral differencing in horizontal planes and solves an elliptic pressure equation is described. As an application, this code is used ...
Peter P. Sullivan; Edward G. Patton
EPIC 95�W Observations of the Eastern Pacific Atmospheric Boundary Layer from the Cold Tongue to the ITCZ
The atmospheric boundary layer (ABL) along 95�W in the eastern equatorial Pacific during boreal autumn is described using data from the East Pacific Investigation of Climate (EPIC) 2001, with an emphasis on the evolution of the thermodynamic ABL ...
Simon P. de Szoeke; Christopher S. Bretherton; Nicholas A. Bond; Meghan F. Cronin; Bruce M. Morley
Large-Scale Structure of the June�July 1996 Marine Boundary Layer along California and Oregon
Data from surface stations, profilers, long-range aircraft surveys, and satellites were used to characterize the large-scale structure of the marine boundary layer off of California and Oregon during June and July 1996. To supplement these ...
C. E. Dorman; T. Holt; D. P. Rogers; K. Edwards
Climatology of the Low-Level Jet at the Southern Great Plains Atmospheric Boundary Layer Experiments Site
A unique dataset obtained with combinations of minisodars and 915-MHz wind profilers at the Atmospheric Boundary Layer Experiments (ABLE) facility in Kansas was used to examine the detailed characteristics of the nocturnal low-level jet (LLJ). In ...
Jie Song; Ke Liao; Richard L. Coulter; Barry M. Lesht
Spatial and Structural Variation of the Atmospheric Boundary Layer during Summer in Israel�Profiler and Rawinsonde Measurements
An opportunity to improve understanding related to the structure of the atmospheric boundary layer (ABL) in Israel along the coastal region environs emerged in April 1997 when the Israel Electric Corporation, Ltd. (IEC), installed and began the ...
Uri Dayan; Batia Lifshitz-Goldreich; Karel Pick
Prediction of continental shelf sediment transport using a theoretical model of the wave-current boundary layer
This thesis presents an application of the Grant-Madsen-Glenn bottom boundary layer model (Grant and Madsen, 1979; Glenn and Grant, 1987) to predictions of sediment transport on the continental shelf. The analysis is a ...
Goud, Margaret R
Dispersion of Particles Released into a Neutral Planetary Boundary Layer Using a Markov Chain�Monte Carlo Model
The dispersion and concentration of particles (fluid elements) that are continuously released into a neutral planetary boundary layer is presented. The velocity fluctuations of the particles are generated using a Markov chain�Monte Carlo (MCMC) ...
R. Avila; S. S. Raza
A Model Study of the Stably Stratified Steady-State Atmospheric Boundary Layer over a Slightly Inclined Terrain
A simple, steady-state, numerical model is used to examine the Rossby-number similarity theory of the atmospheric boundary layer over a slightly inclined terrain. The model confirms the similarity predictions. The slope-influenced universal ...
Zbigniew Sorbjan
Modeling the Atmospheric Convective Boundary Layer within a Zero-Order Jump Approach: An Extended Theoretical Framework
The paper presents an extended theoretical background for applied modeling of the atmospheric convective boundary layer within the so-called zero-order jump approach, which implies vertical homogeneity of meteorological fields in the bulk of ...
Evgeni Fedorovich
Regional Model Simulations of Marine Boundary Layer Clouds over the Southeast Pacific off South America. Part I: Control Experiment
A regional climate model is used to simulate boundary layer stratocumulus (Sc) clouds over the southeast Pacific off South America during August�October 1999 and to study their dynamical, radiative, and microphysical properties and their ...
Yuqing Wang; Shang-Ping Xie; Haiming Xu; Bin Wang
Convective Boundary Layer Depth Estimation from Wind Profilers: Statistical Comparison between an Automated Algorithm and Expert Estimations
A previous study showed success in determining the convective boundary layer depth with radar wind-profiling radars using fuzzy logic methods, and improvements to the earlier work are discussed. The improved method uses the Vaisala multipeak ...
Laura Bianco; James M. Wilczak; Allen B. White
Preliminary Results from Long-Term Measurements of Atmospheric Moisture in the Marine Boundary Layer in the Gulf of Mexico*
Measurements of boundary layer moisture have been acquired from Rotronic MP-100 sensors deployed on two National Data Buoy Center (NDBC) buoys in the northern Gulf of Mexico from June through November 1993. For one sensor that was retrieved ...
Laurence C. Breaker; David B. Gilhousen; Lawrence D. Burroughs
Development and Application of a Compact, Tunable, Solid-State Airborne Ozone Lidar System for Boundary Layer Profiling
The National Oceanic and Atmospheric Administration/Earth System Research Laboratory/Chemical Sciences Division (NOAA/ESRL/CSD) has developed a versatile, airborne lidar system for measuring ozone and aerosols in the boundary layer and lower free ...
R. J. Alvarez II; C. J. Senff; A. O. Langford; A. M. Weickmann; D. C. Law; J. L. Machol; D. A. Merritt; R. D. Marchbanks; S. P. Sandberg; W. A. Brewer; R. M. Hardesty; R. M. Banta
Boundary-Layer Water Vapor Probing with a Solar-Blind Raman Lidar: Validations, Meteorological Observations and Prospects
The ability of a solar-blind Raman lidar (SBRL) to measure the vertical profile of water vapor in the boundary layer is proved from a theoretical as well as an experimental point of view.
D. Renaut; R. Capitini
Time Series Measurements of Chlorophyll Fluorescence in the Oceanic Bottom Boundary Layer with a Multisensor Fiber-Optic Fluorometer
An in situ multisensor fiber-optic fluorometer (MFF) has been developed to acquire long-term chlorophyll fluorescence measurements in the oceanic bottom boundary layer to characterize the finescale pigment structure at vertical spatial scales ...
Eurico J. D�Sa; Steven E. Lohrenz; Vernon L. Asper; Roy A. Walters
Marine Boundary-layer Structure and Circulation in the Region of Offshore Redevelopment of a Cyclone during GALE
Marine boundary-layer structure and circulation is documented for the 24 February 1986 case of offshore redevelopment of a cyclone during the Genesis of Atlantic Lows Experiment (GALE) Intensive Observing Period (IOP) 9. Mesoscale and satellite ...
Teddy Holt; Sethu Raman
Inference of Marine Atmospheric Boundary Layer Moisture and Temperature Structure Using Airborne Lidar and Infrared Radiometer Data
A new technique for retrieving near-surface moisture and profiles of mixing ratio and potential temperature through the depth of the marine atmospheric boundary layer (MABL) using airborne lidar and multichannel infrared radiometer data is ...
Stephen P. Palm; Denise Hagan; Geary Schwemmer; S. H. Melfi
An Observational and Numerical Study of a Sheared, Convective Boundary Layer. Part I: Phoenix II Observations, Statistical Description, and Visualization
Four-dimensional velocity fields derived from dual Doppler radar observations are the basis of a description and statistical analysis of a convective, sheared planetary boundary layer during an afternoon over the High Plains of eastern Colorado. ...
Jeanne M. Schneider; Douglas K. Lilly
Evaluating Weather Research and Forecasting (WRF) Model Predictions of Turbulent Flow Parameters in a Dry Convective Boundary Layer
Weather Research and Forecasting (WRF) model predictions using different boundary layer schemes and horizontal grid spacings were compared with observational and numerical large-eddy simulation data for conditions corresponding to a dry ...
Jeremy A. Gibbs; Evgeni Fedorovich; Alexander M. J. van Eijk
A Combined Local and Nonlocal Closure Model for the Atmospheric Boundary Layer. Part I: Model Description and Testing
The modeling of the atmospheric boundary layer during convective conditions has long been a major source of uncertainty in the numerical modeling of meteorological conditions and air quality. Much of the difficulty stems from the large range of ...
A Climatological Study of Boundary Layer Wind Speed Using a Meso-?-Scale Higher-Order Closure Model
A mesoscale higher-order closure atmospheric boundary layer model has been used to get more detailed information than is possible from observations regarding horizontal and vertical variations of the wind in an area in southeastern Sweden. To ...
Hans Bergstr�m
Doppler Lidar�Based Wind-Profile Measurement System for Offshore Wind-Energy and Other Marine Boundary Layer Applications
Accurate measurement of wind speed profiles aloft in the marine boundary layer is a difficult challenge. The development of offshore wind energy requires accurate information on wind speeds above the surface at least at the levels occupied by ...
Yelena L. Pichugina; Robert M. Banta; W. Alan Brewer; Scott P. Sandberg; R. Michael Hardesty
Horizontal-Velocity and Variance Measurements in the Stable Boundary Layer Using Doppler Lidar: Sensitivity to Averaging Procedures
Quantitative data on turbulence variables aloft�above the region of the atmosphere conveniently measured from towers�have been an important but difficult measurement need for advancing understanding and modeling of the stable boundary layer (SBL)...
Yelena L. Pichugina; Sara C. Tucker; Robert M. Banta; W. Alan Brewer; Neil D. Kelley; Bonnie J. Jonkman; Rob K. Newsom
Relation between Mean Boundary-Layer Structure and Cloudiness at the R/V Valdivia during ASTEX
The relationship between boundary-layer thermodynamic structure and cloud fields and their diurnal variation are explored using seven days of data from dw R/V Valdivia during the Atlantic Stratocumulus Transition Experiment. Cloudiness is at a ...
Alan K. Betts; Christopher S. Bretherton; Ernst Klinker
Numerical Study of Urban Impact on Boundary Layer Structure: Sensitivity to Wind Speed, Urban Morphology, and Rural Soil Moisture
A mesoscale model with a detailed urban surface exchange parameterization is used to study urban influences on boundary layer structure. The parameterization takes into account thermal and mechanical factors, and it is able to reproduce the most ...
Alberto Martilli
Application of a dynamic-stochastic approach to short-term forecasting of the atmospheric boundary layer.
A two-dimensional, dynamic-stochastic model presented in this study is used for short-term forecasting of vertical profiles of air temperature and wind velocity orthogonal components in the atmospheric boundary layer (ABL). The technique of using ...
V. S. Komarov; A. V. Lavrinenko; N. Ya. Lomakina; S. N. Il�in
Eddy Diffusivity/Mass Flux and Shallow Cumulus Boundary Layer: An Updraft PDF Multiple Mass Flux Scheme
In this study, the eddy diffusivity/mass flux (EDMF) approach is used to combine parameterizations of nonprecipitating moist convection and boundary layer turbulence. The novel aspect of this EDMF version is the use of a probability density ...
Kay Su�elj; Jo�o Teixeira; Georgios Matheou
Probability Density Functions of Liquid Water Path and Total Water Content of Marine Boundary Layer Clouds: Implications for Cloud Parameterization
Mathematical forms of probability density functions (PDFs) of liquid water path (LWP) and total water content for marine boundary layer clouds are investigated using the homogeneity, skewness, and kurtosis of PDFs of LWP obtained from observations ...
Hideaki Kawai; Jo�o Teixeira
The Probability Distribution of Sea Surface Wind Speeds: Effects of Variable Surface Stratification and Boundary Layer Thickness
Air�sea exchanges of momentum, energy, and material substances of fundamental importance to the variability of the climate system are mediated by the character of the turbulence in the atmospheric and oceanic boundary layers. Sea surface winds ...
Adam Hugh Monahan
Development and Testing of Instrumentation for UAV-Based Flux Measurements within Terrestrial and Marine Atmospheric Boundary Layers
Instrumentation packages have been developed for small (18�28 kg) unmanned aerial vehicles (UAVs) to measure momentum fluxes as well as latent, sensible, and radiative heat fluxes in the atmospheric boundary layer (ABL) and the topography below. ...
Benjamin D. Reineman; Luc Lenain; Nicholas M. Statom; W. Kendall Melville
Parameterization of Land Surface Processes to Study Boundary Layer Characteristics over a Semiarid Region in Northwest India
The atmospheric boundary layer and land surface processes play a crucial role and affect large-scale phenomena such as monsoons. A comprehensive soil�vegetation parameterization scheme has been developed to understand the complex interaction of ...
A. N. V. Satyanarayana; V. N. Lykossov; U. C. Mohanty; E. E. Machul'skaya
Experimental Study of an Artificial Thermal Plume in the Boundary Layer. Part II: Some Aspects of the Plume Thermodynamical Structure
Some aspects of the mean and turbulent structures of artificial thermal plumes in the boundary layer (BL) are presented. This analysis is based mainly on measurements with an instrumented aircraft. As initial conditions for plume rise, the ...
J. Noilhan; B. B�nech; G. Letrenne; A. Druilhet; A. Saab
The Effects of Nonhomogeneous Surface Fluxes on the Convective Boundary Layer: A Case Study Using Large-Eddy Simulation
Most land surfaces are quasi-randomly nonhomogeneous, yet most boundary-layer studies assume homogeneous or simply varying surface conditions. In this study, nonhomogeneous surface fluxes of realistic scale and amplitude are applied to a large-...
Leslie M. Hechtel; Roland B. Stul; Chin-Hoh Moeng
A Study of the Urban Boundary Layer Using Different Urban Parameterizations and High-Resolution Urban Canopy Parameters with WRF
In the last two decades, mesoscale models (MMs) with urban canopy parameterizations have been widely used to study urban boundary layer processes. Different studies show that such parameterizations are sensitive to the urban canopy parameters (...
Francisco Salamanca; Alberto Martilli; Mukul Tewari; Fei Chen
Seasonal Variability in the Diurnal Evolution of the Boundary Layer in a Near-Coastal Urban Environment
Boundary layer height is estimated during a 21-month period in Houston, Texas, using continuous ceilometer observations and the minimum-gradient method. A comparison with over 60 radiosondes indicates overall agreement between ceilometer- and ...
Christine L. Haman; Barry Lefer; Gary A. Morris
The Modification of Bottom Boundary Layer Turbulence and Mixing by Internal Waves Shoaling on a Barrier Reef
Results are presented from an observational study of stratified, turbulent flow in the bottom boundary layer on the outer southeast Florida shelf. Measurements of momentum and heat fluxes were made using an array of acoustic Doppler velocimeters ...
Kristen A. Davis; Stephen G. Monismith
Turbulence Structure of the Convective Boundary Layer. Part III: The Vertical Velocity Budgets of Thermals and Their Environment
The dynamics of thermal updrafts and compensating environmental downdrafts in the convective boundary layer are examined using observations from the Phoenix 78 field experiment. Separate vertical velocity budgets are presented for thermal ...
Western Pacific Warm Pool Region Sensitivity to Convective Triggering byBoundary Layer Thermals in the NOGAPS Atmospheric GCM
The sensitivity of the atmospheric general circulation model of the Navy Operational Global Atmospheric Prediction System to a parameterization of convective triggering by atmospheric boundary layer thermals is investigated. The study focuses on ...
James A. Ridout; Carolyn A. Reynolds
Modification of the Boundary Layer over the South China Sea during a Winter MONEX Cold Surge Event
Aircraft dropwindsonde and conventional sounding data have been used to document the boundary layer structure over the South China Sea during the period of a 3-day moderate cold surge that occurred during the December 1918 Winter Monsoon ...
Richard H. Johnson; Jeffery R. Zimmerman
Vertical Velocity and Buoyancy Characteristics of Coherent Echo Plumes in the Convective Boundary Layer, Detected by a Profiling Airborne Radar
Aircraft and airborne millimeter-wave radar observations are used to interpret the dynamics of radar echoes and radar-inferred updrafts within the well-developed, weakly sheared continental convective boundary layer. Vertically pointing radar ...
Qun Miao; Bart Geerts; Margaret LeMone
Measurement of Water Vapor Flux Profiles in the Convective Boundary Layer with Lidar and Radar-RASS
A remote-sensing method to retrieve vertical profiles of water vapor flux in the convective boundary layer by using a differential absorption lidar and a radar-radio acoustic sounding system is described. The system's height range presently ...
Christoph Senff; Jens B�senberg; Gerhard Peters
An LES Study of the Impacts of Land Surface Heterogeneity on Dispersion in the Convective Boundary Layer
A systematic analysis of the impacts of heat patches and topographical features on the dispersion of passive materials in a shear-free convective boundary layer (CBL) was performed. Large eddy simulations and a Lagrangian particle dispersion ...
S. G. Gopalakrishnan; Roni Avissar
Numerical solution for mixed convection boundary layer flow of a nanofluid along an inclined plate embedded in a porous medium
The steady mixed convection boundary layer flow of an incompressible nanofluid along a plate inclined at an angle @a in a porous medium is studied. The resulting nonlinear governing equations with associated boundary conditions are solved using an optimized, ... Keywords: FDM, FEM, Inclined plate, Mixed convection, Nanofluid, Porous medium
Puneet Rana; R. Bhargava; O. A. B�G
Relationship between Low-Level Jet Properties and Turbulence Kinetic Energy in the Nocturnal Stable Boundary Layer
In the nighttime stable boundary layer (SBL), shear and turbulence are generated in the layer between the maximum of the low-level jet (LLJ) and the earth's surface. Here, it is investigated whether gross properties of the LLJ�its height and ...
Robert M. Banta; Yelena L. Pichugina; Rob K. Newsom
A field project over the Atmospheric Radiation Measurement-Clouds and Radiation Testbed (ARM-CART) site during a period of several nights in September, 2007 was conducted to explore the evolution of the low-level jet (LLJ). Data was collected from a tower and a sodar and analyzed for turbulent behavior. To study the full range of nocturnal boundary layer (NBL) behavior, the Regional Atmospheric Modeling System (RAMS) was used to simulate the ARM-CART NBL field experiment and validated against the data collected from the site. This model was run at high resolution, and is ideal for calculating the interactions among the various motions within the boundary layer and their influence on the surface. The model reproduces adequately the synoptic situation and the formation and dissolution cycles of the low-level jet, although it suffers from insufficient cloud production and excessive nocturnal cooling. The authors suggest that observed heat flux data may further improve the realism of the simulations both in the cloud formation and in the jet characteristics. In a higher resolution simulation, the NBL experiences motion on a range of timescales as revealed by a wavelet analysis, and these are affected by the presence of the LLJ. The model can therefore be used to provide information on activity throughout the depth of the NBL.
Werth, D.; Kurzeja, R.; Parker, M.
Radial boundary layer structure and Nusselt number in Rayleigh-Benard convection
Results from direct numerical simulations for three dimensional Rayleigh-Benard convection in a cylindrical cell of aspect ratio 1/2 and Pr=0.7 are presented. They span five decades of Ra from $2\\times 10^6$ to $2 \\times10^{11}$. Good numerical resolution with grid spacing $\\sim$ Kolmogorov scale turns out to be crucial to accurately calculate the Nusselt number, which is in good agreement with the experimental data by Niemela et al., Nature, 404, 837 (2000). In underresolved simulations the hot (cold) plumes travel further from the bottom (top) plate than in the fully resolved case, because the thermal dissipation close to the sidewall (where the grid cells are largest) is insufficient. We compared the fully resolved thermal boundary layer profile with the Prandtl-Blasius profile. We find that the boundary layer profile is closer to the Prandtl Blasius profile at the cylinder axis than close to the sidewall, due to rising plumes in that region.
Stevens, Richard J A M; Lohse, Detlef
Numerical Characteriztion of the Fracture Behavior of Solid Oxide Fuel Cell Materials by Means of Modified Boundary Layer Modeling
A modified boundary layer modeling approach is used to predict the fracture toughness and crack resistance behaviors of solid oxide fuel cell (SOFC) materials. In this approach, a pre-existing crack inside a layer or at an interface between two different layers is assumed under plane strain conditions. Fracture is allowed to occur in a small process window situated at the crack tip. The process window is contained in a circular region, which can involve two different materials and their interface. Elastic asymptotic crack-tip fields are prescribed as remote boundary conditions. Special attention focuses on the cracking of the interface between the glass seal and the electrolyte material.
Nguyen, Ba Nghiep; Koeppel, Brian J.; Singh, Prabhakar; Khaleel, Mohammad A.; Ahzi, Said
Coupled Mesoscale-Large-Eddy Modeling of Realistic Stable Boundary Layer Turbulence
Site-specific flow and turbulence information are needed for various practical applications, ranging from aerodynamic/aeroelastic modeling for wind turbine design to optical diffraction calculations. Even though highly desirable, collecting on-site meteorological measurements can be an expensive, time-consuming, and sometimes a challenging task. In this work, we propose a coupled mesoscale-large-eddy modeling framework to synthetically generate site-specific flow and turbulence data. The workhorses behind our framework are a state-of-the-art, open-source atmospheric model called the Weather Research and Forecasting (WRF) model and a tuning-free large-eddy simulation (LES) model. Using this coupled framework, we simulate a nighttime stable boundary layer (SBL) case from the well-known CASES-99 field campaign. One of the unique aspects of this work is the usage of a diverse range of observations for characterization and validation. The coupled models reproduce certain characteristics of observed low-level jets....
Wang, Yao; Manuel, Lance
Influence of nosetip shape on boundary layer transition in arc heated jets
The effect of model shape on the graphite recession rate and boundary layer transition was studied in an arc jet over the pressure and enthalpy ranges of 0.99 to 20.7 MPa (9.8 to 204 atm) and 3416 to 15640J/g (1470 to 6730 Btu;lb), respectively. Hemispheric, flat-faced and conic cylindrical models were used. It was found that resistance to transition occurs in the order of flat-faced > conic > hemispheric shape. Evidence of this behavior is provided in terms of the relative ablation rates associated with each shape and the times-to-transition. The differences in resistance to transition are appreciable and suggest that reentry vehicles would benefit with respect to nosetip shape change by changing from the conventional hemispheric shape to a conic or, preferably, a flat-faced configuration.
Auerbach, I.
RACORO Extended-Term Aircraft Observations of Boundary-Layer Clouds
A first-of-a-kind, extended-term cloud aircraft campaign was conducted to obtain an in-situ statistical characterization of boundary-layer clouds needed to investigate cloud processes and refine retrieval algorithms. Coordinated by the Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF), the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign operated over the ARM Southern Great Plains (SGP) site from 22 January to 30 June 2009, collecting 260 h of data during 59 research flights. A comprehensive payload aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft measured cloud microphysics, solar and thermal radiation, aerosol properties, and atmospheric state parameters. Proximity to the SGP's extensive complement of surface measurements provides ancillary data that supports modeling studies and enables evaluating a variety of surface retrieval algorithms. The five-month duration enabled sampling a range of conditions associated with the seasonal transition from winter to summer. Although about two-thirds of the cloud flights occurred in May and June, boundary-layer cloud fields were sampled under a variety of environmental and aerosol conditions, with about 75% of the flights occurring in cumulus and stratocumulus. Preliminary analyses show how these data are being used to analyze cloud-aerosol relationships, determine the aerosol sizes that are responsible for nucleating cloud drops, characterize the horizontal variability of the cloud radiative impacts, and evaluate air-borne and surface-based cloud property retrievals. We discuss how conducting an extended-term campaign requires a simplified operating paradigm that is different from that used for typical, short-term, intensive aircraft field programs.
Vogelmann, A. M.; McFarquhar, Greg; Ogren, John A.; Turner, David D.; Comstock, Jennifer M.; Feingold, G.; Long, Charles N.; Jonsson, Haf; Bucholtz, Anthony; Collins, Donald R.; Diskin, G. S.; Gerber, H.; Lawson, Paul; Woods, Roy; Andrews, Elizabeth; Yang, Hee-Jung; Chiu, Christine J.; Hartsock, Daniel; Hubbe, John M.; Lo, Chaomei; Marshak, A.; Monroe, Justin; McFarlane, Sally A.; Schmid, Beat; Tomlinson, Jason M.; Toto, Tami
Boundary-Layer Receptivity to Three-Dimensional Roughness Arrays on a Swept-Wing
On-going efforts to reduce aircraft drag through transition delay focus on understanding the process of boundary-layer transition from a physics-based perspective. For swept-wings subject to transition dominated by a stationary crossflow instability, one of the remaining challenges is understanding how freestream disturbances and surface features such as surface roughness create the initial amplitudes for unstable waves. These waves grow, modify the mean flow and create conditions for secondary instabilities to occur, which in turn ultimately lead to transition. Computational methods that model the primary and secondary instability growth can accurately model disturbance evolution as long as appropriate initial conditions are supplied. Additionally, transition delay using discrete roughness arrays that exploit known sensitivities to surface roughness has been demonstrated in flight and wind tunnel testing; however, inconsistencies in performance from the two test platforms indicate further testing is required. This study uses detailed hotwire boundary-layer velocity scans to quantify the relationship between roughness height and initial disturbance amplitude. Naphthalene flow visualization provides insight into how transition changes as a result of roughness height and spacing. Micron-sized, circular roughness elements were applied near the leading edge of the ASU(67)-0315 model installed at an angle of attack of -2.9 degrees in the Klebanoff-Saric Wind Tunnel. Extensive flow quality measurements show turbulence intensities less than 0.02% over the speed range of interest. A survey of multiple roughness heights for the most unstable and control wavelengths and Reynolds numbers of 2.4 x 10? 2.8 x 10? and 3.2 x 10? was completed for chord locations of 10%, 15% and 20%. When care was taken to measure in the region of linear stability, it was found that the disturbance amplitude varies almost linearly with roughness height. Naphthalene flow visualization indicates that moderate changes in already-low freestream turbulence levels can have a significant impact on transition behavior.
Hunt, Lauren Elizabeth
Catalyzed combustion in a flat plate boundary layer. II. Numerical calculations
A computer program has been developed to solve the boundary layer equations for laminar flow over a heated plate with H/sub 2//air combustion. The objectives are to investigate the importance of homogeneous as opposed to catalytic surface reactions during the combustion process, and to determine the roles of heat and mass transfer and their effect on combustion. Results are presented for combustion of H/sub 2//air at an equivalence ratio of 0.1 for flow over a noncatalytic plate at a surface temperature of 1100/sup 0/K. A detailed mechanism involving 8 chemical species and 13 reactions has been used to describe the kinetics. The reactions leading to the initiation of combustion and the effect of the large diffusivity of hydrogen are discussed. The boundary conditions for catalytic surface and a simplified model to account for catalytic wall reaction are formulated. Results are presented for combustion over a catalytic surface and compared with the non-catalytic case.
Schefer, R.; Robben, F.
Nocturnal Low-Level-Jet-Dominated Atmospheric Boundary Layer Observed by a Doppler Lidar Over Oklahoma City during JU2003
Boundary layer wind data observed by a Doppler lidar and sonic anemometers during the mornings of three intensive observational periods (IOP2, IOP3, and IOP7) of the Joint Urban 2003 (JU2003) field experiment are analyzed to extract the mean and turbulent characteristics of airflow over Oklahoma City, Oklahoma. A strong nocturnal low-level jet (LLJ) dominated the flow in the boundary layer over the measurement domain from midnight to the morning hours. Lidar scans through the LLJ taken after sunrise indicate that the LLJ elevation shows a gradual increase of 25-100 m over the urban area relative to that over the upstream suburban area. The mean wind speed beneath the jet over the urban area is about 10%-15% slower than that over the suburban area. Sonic anemometer observations combined with Doppler lidar observations in the urban and suburban areas are also analyzed to investigate the boundary layer turbulence production in the LLJ-dominated atmospheric boundary layer. The turbulence kinetic energy was higher over the urban domain mainly because of the shear production of building surfaces and building wakes. Direct transport of turbulent momentum flux from the LLJ to the urban street level was very small because of the relatively high elevation of the jet. However, since the LLJ dominated the mean wind in the boundary layer, the turbulence kinetic energy in the urban domain is correlated directly with the LLJ maximum speed and inversely with its height. The results indicate that the jet Richardson number is a reasonably good indicator for turbulent kinetic energy over the urban domain in the LLJ-dominated atmospheric boundary layer.
Wang, Yansen; Klipp, Cheryl L.; Garvey, Dennis M.; Ligon, David; Williamson, Chatt C.; Chang, Sam S.; Newsom, Rob K.; Calhoun, Ron
Comparing modeled isoprene with aircraft-based measurements in the atmospheric boundary layer.
Nonmethane hydrocarbons (NMHCs) are involved in a complex series of reactions that regulate the levels of oxidants in the troposphere. Isoprene (C{sub 5}H{sub 8}), the primary NMHC emitted from deciduous trees, is one of the most important reactive hydrocarbons in the troposphere. The amount of isoprene entering the free troposphere is regulated by the compound's rate of emission from leaves and by chemical and physical processes in the forest canopy and the atmospheric boundary layer (ABL). This study uses a coupled canopy-ABL model to simulate these complex processes and compares calculated isoprene concentration profiles with those measured during aircraft flights above a forested region in the northeastern US. Land use information is coupled with satellite remote sensing data to describe spatial changes in canopy density during the field measurements. The high-resolution transport-chemistry model of Gao et al. (1993) for the ABL and the forest canopy layer is used to simulate vertical changes in isoprene concentration due to turbulent mixing and chemical reactions. The one-dimensional (1-D) ABL model includes detailed radiation transfer, turbulent diffusion, biogenic emissions, dry deposition, and chemical processes within the forest canopy and the ABL. The measured profiles are compared with the model simulations to investigate the biological, physical, and chemical processes that regulate the levels of isoprene within the ABL.
Doskey, P.; Gao, W.
The RED Experiment: An Assessment of Boundary Layer Effects in a Trade Winds Regime on Microwave and Infrared Propagation over the Sea
In the surface layer over the ocean the Monin�Obukhov similarity theory is often applied to construct vertical profiles of pressure, temperature, humidity, and wind speed. In this context, the rough boundary layer is derived from empirical ...
Kenneth Anderson; Stephen Doss-Hammel; Dimitris Tsintikidis; Barbara Brooks; Michael Smith; Peter Caffrey; Antony Clarke; Leo Cohen; Arie De Jong; Gerrit De Leeuw; Marcel Moerman; Katie Crahan; Kenneth Davidson; Paul Frederickson; Denis Dion; Carl Friehe; Djamal Khelif; Tihomir Hristov; Jeffery S. Reid; Steven Reising; Eric Terrill
Wind profile above the surface boundary layer S.-E. Gryning (1), E. Batchvarova (2) and B. Brmmer (3)
Wind profile above the surface boundary layer S.-E. Gryning (1), E. Batchvarova (2) and B. Brümmer in predictions of the wind profile in the lowest hundreds me- ters of the atmosphere, being connected to the general increase in height of structures such as bridges, high houses and wind turbines. The hub height
A Mixed Spectral Finite-Difference 3D Model of Neutral Planetary Boundary-Layer Flow over Topography
A simple three-dimensional linear model of planetary boundary-layer flow is developed based on the Mixed Spectral Finite-Difference model of Beljaars et al. using the full second-order turbulence closure of Launder et al. The model uses a steady-...
Keith W. Ayotte; Peter A. Taylor
A Unified Model for Moist Convective Boundary Layers Based on a Stochastic Eddy-Diffusivity/Mass-Flux Parameterization
A single-column model (SCM) is developed for representing moist convective boundary layers. The key component of the SCM is the parameterization of subgrid-scale vertical mixing, which is based on a stochastic eddy-diffusivity/mass-flux (EDMF) ...
Kay Su�elj; Jo�o Teixeira; Daniel Chung
Quasi-Lagrangian Large Eddy Simulations of Cross-Equatorial Flow in the East Pacific Atmospheric Boundary Layer
Using a large eddy simulation (LES), the atmospheric boundary layer (ABL) is numerically modeled along 95�W from 8�S to 4�N during boreal autumn, and compared to observations from the East Pacific Investigation of Climate Processes in the Coupled ...
S. P. de Szoeke; C. S. Bretherton
Estimation of Dissipative Heating Using Low-Level In Situ Aircraft Observations in the Hurricane Boundary Layer
Data collected in the low-level atmospheric boundary layer in five hurricanes by NOAA research aircraft are analyzed to measure turbulence with scales small enough to retrieve the rate of dissipation. A total of 49 flux runs suitable for analysis ...
Jun A. Zhang
Atmospheric boundary layer parameters necessary for calculation of gas and particle deposition velocities were directly measured from
Results Atmospheric boundary layer parameters necessary for calculation of gas and particle hourly gas and particle deposition velocities. Acknowledgements · Staffs at the Lost Dutchman State Park, Desert Botanical Garden, and White Tank Mountain Regional Park. · Fred Peña, Department of Chemical
Hall, Sharon J.
Measurement of Vertical Kinetic Energy and Vertical Velocity Skewness in Oceanic Boundary Layers by Imperfectly Lagrangian Floats
The effects of upward buoyancy on the accuracy with which Lagrangian floats can measure the Eulerian mean variance wwE and skewness SwE of vertical fluid velocity w in the wind-driven upper-ocean boundary layer is investigated using both ...
Ramsey R. Harcourt; Eric A. D�Asaro
Meteorological Tower, Microbarograph Array, and Sodar Observations of Solitary-like Waves in the Nocturnal Boundary Layer
Five short-duration disturbances of the stable nocturnal boundary layer, ranging in depth from about 15 m to over 500 m, were observed using a 300 m meteorological tower, 2 sodars, and a 4-station microbarograph array. Four of the events showed ...
T. K. Cheung; C. G. Little
The Behavior of Passive and Buoyant Plumes in a Convective Boundary Layer, as Simulated with a Large-Eddy Model
With a large-eddy model the large-scale flow structure of the convective boundary layer is simulated in a box of (5 � 5 � 2) km. The calculation is run till the turbulence has reached a quasi-steady state. At that time we introduce a line-source ...
L. van Haren; F. T. M. Nieuwstadt
Statistics of Absolute and Relative Dispersion in the Atmospheric Convective Boundary Layer: A Large-Eddy Simulation Study
The influence of the different scales of turbulent motion on plume dispersion in the atmospheric convective boundary layer (CBL) is studied by means of a large-eddy simulation (LES). In particular, the large-scale (meandering) and small-scale (...
Alessandro Dosio; Jordi Vil�-Guerau de Arellano
An Observation System Used To Study the Marine Boundary Layer Over the Bay of Bengal During Summer Monex 79
An observation system used to study the marine boundary layer over the Bay of Bengal at Digha Beach, West Bengal, India, as part of the International Monsoon Experiments (MONEX 79) is described in this paper. It was a portable system that was ...
S. SethuRaman; P. Michael; W. A. Tuthill; J. McNeil
The Boundary Layer Response to Recent Arctic Sea Ice Loss and Implications for High-Latitude Climate Feedbacks
This study documents and evaluates the boundary layer and energy budget response to record low 2007 sea ice extents in the Community Atmosphere Model version 4 (CAM4) using 1-day observationally constrained forecasts and 10-yr runs with a freely ...
J. E. Kay; K. Raeder; A. Gettelman; J. Anderson
Nocturnal Low-Level-Jet-Dominated Atmospheric Boundary Layer Observed by a Doppler Lidar over Oklahoma City during JU2003
Boundary layer wind data observed by a Doppler lidar and sonic anemometers during the mornings of three intensive observational periods (IOP2, IOP3, and IOP7) of the Joint Urban 2003 (JU2003) field experiment are analyzed to extract the mean and ...
Yansen Wang; Cheryl L. Klipp; Dennis M. Garvey; David A. Ligon; Chatt C. Williamson; Sam S. Chang; Rob K. Newsom; Ronald Calhoun
A Numerical Study of the Interaction between a Deep Cold Jet and the Bottom Boundary Layer of the Ocean
A two-dimensional (x-z) primitive equation model is used to study the interaction between a deep cold jet on a sloping bottom and the bottom boundary layer (BBL) of the deep ocean. Two closure schemes are used: a standard second order turbulence ...
Tal Ezer; Georges L. Weatherly
Analysis of a Radome Air-Motion System on a Twin-Jet Aircraft for Boundary-Layer Research
A �radome gust probe� system was installed on a twin-jet aircraft for the purpose of boundary-layer research. This system provided a useful relatively low-cost method for air motion and turbulence measurements on an aircraft already equipped with ...
Michael Tjernstr�m; Carl A. Friehe
Twenty-Four-Hour Observations of the Marine Boundary Layer Using Shipborne NOAA High-Resolution Doppler Lidar
Shipborne observations obtained with the NOAA high-resolution Doppler lidar (HRDL) during the 1999 Nauru (Nauru99) campaign were used to study the structure of the marine boundary layer (MBL) in the tropical Pacific Ocean. During a day with weak ...
Volker Wulfmeyer; Tijana Janji?
We perform global unstratified three-dimensional magnetohydrodynamic simulations of an astrophysical boundary layer (BL)-an interface region between an accretion disk and a weakly magnetized accreting object such as a white dwarf-with the goal of understanding the effects of magnetic field on the BL. We use cylindrical coordinates with an isothermal equation of state and investigate a number of initial field geometries including toroidal, vertical, and vertical with zero net flux. Our initial setup consists of a Keplerian disk attached to a non-rotating star. In a previous work, we found that in hydrodynamical simulations, sound waves excited by shear in the BL were able to efficiently transport angular momentum and drive mass accretion onto the star. Here we confirm that in MHD simulations, waves serve as an efficient means of angular momentum transport in the vicinity of the BL, despite the magnetorotational instability (MRI) operating in the disk. In particular, the angular momentum current due to waves is at times larger than the angular momentum current due to MRI. Our results suggest that angular momentum transport in the BL and its vicinity is a global phenomenon occurring through dissipation of waves and shocks. This point of view is quite different from the standard picture of transport by a local anomalous turbulent viscosity. In addition to angular momentum transport, we also study magnetic field amplification within the BL. We find that the field is indeed amplified in the BL, but only by a factor of a few, and remains subthermal.
Belyaev, Mikhail A.; Rafikov, Roman R.; Stone, James M., E-mail: firstname.lastname@example.com [Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08540 (United States)
Stability and Turbulence in the Atmospheric Boundary Layer: A Comparison of Remote Sensing and Tower Observations
When monitoring winds and atmospheric stability for wind energy applications, remote sensing instruments present some advantages to in-situ instrumentation such as larger vertical extent, in some cases easy installation and maintenance, measurements of vertical humidity profiles throughout the boundary layer, and no restrictions on prevailing wind directions. In this study, we compare remote sensing devices, Windcube lidar and microwave radiometer, to meteorological in-situ tower measurements to demonstrate the accuracy of these measurements and to assess the utility of the remote sensing instruments in overcoming tower limitations. We compare temperature and wind observations, as well as calculations of Brunt-Vaisala frequency and Richardson numbers for the instrument deployment period in May-June 2011 at the U.S. Department of Energy National Renewable Energy Laboratory's National Wind Technology Center near Boulder, Colorado. The study reveals that a lidar and radiometer measure wind and temperature with the same accuracy as tower instruments, while also providing advantages for monitoring stability and turbulence. We demonstrate that the atmospheric stability is determined more accurately when the liquid-water mixing ratio derived from the vertical humidity profile is considered under moist-adiabatic conditions.
Friedrich, K.; Lundquist, J. K.; Aitken, M.; Kalina, E. A.; Marshall, R. F.
Numerical Simulation of the Effects of St. Louis on Mesoscale Boundary-Layer Airflow and Vertical Air Motion: Simulations of Urban vs Non-Urban Effects
A three-dimensional mesoscale computer model is used to assess the importance of urban effects, relative to non-urban effects, on mesoscale boundary-layer vertical air motion and on the height of the boundary layer downwind of St. Louis, ...
Mark R. Hjelmfelt
Analysis and identification of vortices within a turbulent channel boundary layer flow
Vortical structures are regarded as the dominant organized patterns in wall turbulence. They play a key role in physical phenomena of practical importance such as energy and momentum transport, combustion, mixing, and noise and drag production. Considerable investigations have been performed in drag and noise phenomena studies, with a main purpose of controlling and reducing them. Various techniques to control the drag reduction have been studied for over last five decades; however, the detailed understanding of the drag reduction mechanism is still lacking. Vortices play an important role in turbulence structure. Nevertheless, the identification of vortices is still unclear, not even a universal definition of a vortex is accepted. In the present study, several vortex feature extraction schemes are implemented. The methods are applied to analyze instantaneous two-dimensional velocity fields obtained by particle tracking Velocimetry (PTV) measurements of a turbulent channel flow with and without microbubble injection within the boundary layer. Microbubble injection is one of the drag reduction techniques, first studied in early 1970s, that has undergone extensive research in past years, and the generated information has aided into drag reduction understanding. As a general rule, vortex extraction methods can be either a simple visualization scheme or more sophisticated identification tools. The Reynolds decomposition and its variants are suitable due to their capacity to mark vortices advecting at different velocities. In the case of identification techniques, which yield a scalar field calculated from either the velocity vector field or the velocity gradient tensor, both the modified swirling strength ?ci or the ?2 criteria were found to be well suited for vortex identification.
Maroni Veiga, Adrian Gaston
Retrieval of Urban Boundary Layer Structures from Doppler Lidar Data. Part I: Accuracy Assessment
Two coherent Doppler lidars from the US Army Research Laboratory (ARL) and Arizona State University (ASU) were deployed in the Joint Urban 2003 atmospheric dispersion field experiment (JU2003) held in Oklahoma City. The dual lidar data are used to evaluate the accuracy of the four-dimensional variational data assimilation (4DVAR) method and identify the coherent flow structures in the urban boundary layer. The objectives of the study are three-fold. The first objective is to examine the effect of eddy viscosity models on the quality of retrieved velocity data. The second objective is to determine the fidelity of single-lidar 4DVAR and evaluate the difference between single- and dual-lidar retrievals. The third objective is to correlate the retrieved flow structures with the ground building data. It is found that the approach of treating eddy viscosity as part of control variables yields better results than the approach of prescribing viscosity. The ARL single-lidar 4DVAR is able to retrieve radial velocity fields with an accuracy of 98% in the along-beam direction and 80-90% in the cross-beam direction. For the dual-lidar 4DVAR, the accuracy of retrieved radial velocity in the ARL cross-beam direction improves to 90-94%. By using the dual-lidar retrieved data as a reference, the single-lidar 4DVAR is able to recover fluctuating velocity fields with 70-80% accuracy in the along-beam direction and 60-70% accuracy in the cross-beam direction. Large-scale convective roll structures are found in the vicinity of downtown airpark and parks. Vortical structures are identified near the business district. Strong updrafts and downdrafts are also found above a cluster of restaurants.
Xia, Quanxin; Lin, Ching Long; Calhoun, Ron; Newsom, Rob K.
Vehicle cabin cooling system for capturing and exhausting heated boundary layer air from inner surfaces of solar heated windows
DOE Patents (OSTI)
The cabin cooling system includes a cooling duct positioned proximate and above upper edges of one or more windows of a vehicle to exhaust hot air as the air is heated by inner surfaces of the windows and forms thin boundary layers of heated air adjacent the heated windows. The cabin cooling system includes at least one fan to draw the hot air into the cooling duct at a flow rate that captures the hot air in the boundary layer without capturing a significant portion of the cooler cabin interior air and to discharge the hot air at a point outside the vehicle cabin, such as the vehicle trunk. In a preferred embodiment, the cooling duct has a cross-sectional area that gradually increases from a distal point to a proximal point to the fan inlet to develop a substantially uniform pressure drop along the length of the cooling duct. Correspondingly, this cross-sectional configuration develops a uniform suction pressure and uniform flow rate at the upper edge of the window to capture the hot air in the boundary layer adjacent each window.
Farrington, Robert B. (Golden, CO); Anderson, Ren (Broomfield, CO)
Aircraft Measurements of Turbulence Spectra in the Marine Stratocumulus-topped Boundary Layer
Mixed-layer scaling was successfully applied to the velocity, temperature, and moisture spectra of the marine stratocumulus-topped mixed layers observed during the First ISCCP Regional Experiment (FIRE). These turbulence spectra provide ...
Jeffrey J. Nucciarone; George S. Young
Simple Solutions to Steady-state Cumulus Regimes in the Convective Boundary Layer
A modeling framework is developed which extends the mixed layer model to steady state cumulus convection. The aim is to consider the simplest model which retains the essential behavior of cumulus-capped layers. The presented framework allows for ...
Jer�me Schalkwijk; Harmen J. J. Jonker; A. Pier Siebesma
Seismic and gravitational studies of melting in the mantle's thermal boundary layers
This thesis presents three studies which apply geophysical tools to the task of better understanding mantle melting phenomena at the upper and lower boundaries of the mantle. The first study uses seafloor bathymetry and ...
Van Ark, Emily M
Radiative Properties of Boundary Layer Clouds: Droplet Effective Radius versus Number Concentration
The plane-parallel model for the parameterization of clouds in global climate models is examined in order to estimate the effects of the vertical profile of the microphysical parameters on radiative transfer calculations for extended boundary ...
Jean-Louis Brenguier; Hanna Pawlowska; Lothar Sch�ller; Rene Preusker; J�rgen Fischer; Yves Fouquart
Evaluating the Performance of Planetary Boundary Layer and Cloud Microphysical Parameterization Schemes in Convection-Permitting Ensemble Forecasts using Synthetic GOES-13 Satellite Observations
In this study, the ability of several cloud microphysical and planetary boundary layer parameterization schemes to accurately simulate cloud characteristics within 4-km-grid-spacing ensemble forecasts over the contiguous U.S. was evaluated through ...
Rebecca Cintineo; Jason A. Otkin; Ming Xue; Fanyou Kong
A Numerical Model for Chemical and Meteorological Processes in the Atmospheric Boundary Layer. Part I: A Model Description and a One-Dimensional Parameter Study
A numerical flow model is presented for the atmospheric boundary layer, including dispersion and chemical transformations of air pollutants. The model is a three-dimensional time-dependent one for the mesoscale based on the conservation equations ...
Gunilla Svensson
Assimilation of Surface-Based Boundary Layer Profiler Observations during a Cool-Season Weather Event Using an Observing System Simulation Experiment. Part I: Analysis Impact
In this study, an Observing System Simulation Experiment was used to examine how the assimilation of temperature, water vapor, and wind profiles from a potential array of ground-based remote sensing boundary layer profiling instruments impacts the ...
Jason A. Otkin; Daniel C. Hartung; David D. Turner; Ralph A. Petersen; Wayne F. Feltz; Erik Janzon
The Dryline on 22 May 2002 during IHOP: Ground-Radar and In Situ Data Analyses of the Dryline and Boundary Layer Evolution
On the afternoon and evening of 22 May 2002, high-resolution observations of the boundary layer (BL) and a dryline were obtained in the eastern Oklahoma and Texas panhandles during the International H2O Project. Using overdetermined multiple-...
Michael S. Buban; Conrad L. Ziegler; Erik N. Rasmussen; Yvette P. Richardson
Assimilating Coherent Doppler Lidar Measurements into a Model of the Atmospheric Boundary Layer. Part I: Algorithm Development and Sensitivity to Measurement Error
A four-dimensional variational data assimilation (4DVAR) algorithm for retrieval of spatially and temporally resolved velocity and thermodynamic fields within the atmospheric boundary layer (ABL) is described and applied to a coherent Doppler ...
Rob K. Newsom; Robert M. Banta
A Model for Particle Microphysics, Turbulent Mixing, and Radiative Transfer in the Stratocumulus-Topped Marine Boundary Layer and Comparisons with Measurements
A detailed 1D model of the stratocumulus-topped marine boundary layer is described. The model has three coupled components: a microphysics module that resolves the size distributions of aerosols and cloud droplets, a turbulence module that treats ...
Andrew S. Ackerman; Peter V. Hobbs; Owen B. Toon