How is global greenhouse gas emission calculated?

Your question is simple enough, but the answer depends on what exactly you're looking for.

Who is emitting where right now?

Real-time global monitoring of greenhouse gas emissions with a high spatial resolution is an emerging technology.  We have very useful satellites (see Jean-Marie Privals answer), but they have limitations:

All existing public satellites with instruments for high-resolution GHG measurements are in low Earth orbit, so they only see a particular place when they pass over, not all the time.  So far only the Geostationary Interferometric Infrared Sounder (GIIRS) on the Chinese FengYung (FY)-4A satellite can in theory monitor CO₂ from a geostationary viewpoint, which allows for "continuous" monitoring (probably meaning hourly; it takes a while to scan the area of interest), but from what I've heard GIIRS is not performing very well.  Europe plans to launch the Infra-Red Sounder (IRS) in 2023.  Either way, their spatial resolution will be much worse than for the low Earth orbit satellites, because geostationary orbit is so far away.
They rely on visible radiation.  Although attempts to retrieve from infrared radiation exist, their information content is quite poor (for an Arctic methane example, see Holl et al. (2016)).  In Jean-Marie Privals answer you can see an illustration of how reflected sunlight is used as a retrieval.
They usually need clear skies.  We can't look below the clouds, but even retrieving above the cloud would require a very accurate characterisation of the cloud, and clouds are tricky.  So usually we just assume that the GHG concentration is the same with or without clouds, even when it probably isn't.
Some private satellites exist with a very high spatial resolution, but I can't find much verifiable information about them.  GHGSat claims a spatial resolution of less than 50 metre.  Inevitably, that comes at the cost of field of view (12×12 km² claimed), it will only view a spot when actively pointing, so although it may be able to point anywhere on Earth, it will only view very specific areas and is in that sense not global.  It appears many similar commercial instruments are planned in the near future.

  I can imagine a satellite observation-based model that calculates emissions on a spatial basis but I am not sure if our technology is advanced enough to do that accurately. However, this method would not allow segregation of GHG by source/sectors (electricity generation, cement production, agriculture etc.)

The spatial resolution of about 2 km may be good enough for that, unless the electricity plant is next to the cement producer, the emissions occur at night, the factory is switched off when the satellite happens to pass over, or it's cloudy (there are attempts to retrieve in the presence of clouds, but it's harder).

So while satellites are certainly very useful in GHG monitoring, it's difficult to get everything from satellites alone.

Where were emissions last month?

We can average daytime GHG contentration measurements over the period of a month.  Combined with chemistry and circulation models, we can then try to estimate in what regions of the Earth those emissions may have occurred, but not with a precision high enough to tell "electricity or cement".  This is an average of CO₂ measurements for July 2009:

The limitations are less serious now: the satellite has multiple attempts to capture a particular scene, and will usually see at least one clear-sky overpass per month, probably multiple.  In the image above, there was probably also some form of data fusion to combine with other sources or fill gaps using neighbouring pixels.  The longer the time period we average over, the smoother the distribution will look.

What were global emissions last year?

However, if you are looking for global emissions averaged over a long time period, we can make use of the observation that CO₂, and to a lesser degree CH₄, is a well-mixed gas.  Here, well-mixed means that it stays long enough in the atmosphere to reach pretty much everywhere given enough time.  That means that ultimately, it doesn't matter where you emit.  That's why "global" CO₂ concentrations may be measured at Mauna Kea (Hawaii, USA), even though this is far away from any emissions.  However, that also means that it doesn't tell us whether the CO₂ was emitted in India, Italy, or Idaho.  And much of the emitted CO₂ gets absorbed by the oceans, so the delta between this year and last is not enough to determine global emissions.


What are the scientific consequences of the lost of the Nereus submersible?

Nereus as is, is currently not replaceable, but it was insured at a replacement value of $3.1 million, and my understanding Woods Hole currently plans to replace it, though unlikely at this point that there's a solid timeline for this taking place.

Landers, fish traps, and sediment core samplers will still be actively used, but again, these are not really comparable to the areas of research that Nereus was able to cover.

UPDATE: These appears to be the last log entry for the Kermadec Trench 2014 expedition, and the official statement on the day of the event.


From this paper from 1958 (page 2),

  ... gaseous nitrogen of the atmosphere represents a vast store of potential
  fertility. It is not directly available to plants. Nitrogen-fixing bacteria, how-
  ever, absorb this gas from the soil solution and convert it to cell protein.
  When the cells die, other microbes attack the protein and convert the nitro-
  genous constituents to ammonium, which then becomes an available nutrient.
  Similarly, microbial action on plant and animal residues releases the many
  combined nutrients from their unavailable forms.

From this, one of the criteria for soil to be fertile is the availability of nitrogen to be available to plants in a readily usable form. In a two stage process, one group of microbes (bacteria) fixes the nitrogen by converting into a protein, within their cells. When this group of microbes die, another group of microbes uses these proteins to produce ammonia, which is a nutrient that plants can use.

Also, as this article states, dead bacteria are critical to soil fertility, because nearly 40 percent of a the biomass of bacteria are converted to organic soil components.
strong text

The Nitrogen Cycle


How does one interpret negative geopotential height values?

This likely means that the surface MSLP is less than 1000 mb.

If you are looking at a 1000 mb geopotential height, and the MSLP at a point is 995 mb, then the height of the 1000 mb geopotential surface would be below the ground, i.e. negative height.

Effectively the question was what does a negative difference of distance from a pressure surface mean? The answer is that the surface must lie below the frame of reference. In the example, the frame of reference is the ground and the surface is the 1000 mb surface.


Inorganic Limestone and Inorganic Gypsum

Limestone is a sedimentary rock made up mainly of the mineral calcite (calcium carbonate). It may be made up of biogenic calcite such as shells or inorganic calcite deposited as fine grained "micrite" although some micrite may also have a biological origin.

Animals don't have bones made from gypsum so all gypsum deposits have non-biological origin.


The higher value range for the same satellite product (NO2_OMI_TEMIS)

It seems that you are concerned that your values in the data go above the max value on the color bar shown in the kml file.  I wouldn't worry about that.  You are using the "level 3" monthly average product, which by definition is highly quality controlled.  For most of the globe, typical values will vary between 1 x 10^14 and 5 x 10^15 molec/cm2.  Values over 20 x 10^15 molec/cm2 only occur in highly polluted areas.  Very large values in the OMI NO2 product are realistic, especially in SE Asia, where the largest NO2 columns are obtained.  I have even seen values over 1 x 10^17 on occasion.  As the signal gets larger, there is actually more confidence in the retrieval.  Really it's the low values (e.g. less than 8 x 10^14 molec/cm2) that you should treat cautiously, as anything lower than that could be "noise".

In order to show the variance of values (which can span 4 orders of magnitude) across the whole globe, the color scale chosen works well.  Note that the color bar is a logarithmic scale, which helps give definition to the plots in the regions with typical values.  You could rewrite the kml file though, and pick a different max value, if you are interested in better plots of southeast Asia.

If you are interested in learning more about the product, I highly suggest you see Boersma (2011) and also refer to the user manual.


How can I improve the numerical stability of a coastal hydrodynamic model?

Almost all finite methods that use forward time models adhere to the Courant-Friedrichs-Lewy law which calculates a courant number and compares it to a $C_{max}$, which is what determines stability, so for 2-D:

$$C = \frac {V_xdt}{dx}  + \frac{V_ydt}{dy} \ge C_{max}$$

Where $C$ is the courant number, $V_i$ is the velocity in subscripted direction, $dx$ or $dy$ is the length interval in specified direction and $dt$ is the specified time step. If you are getting numerical instability, increasing the mesh spacing will lower the courant number, but then you might be missing the dynamics you want to capture. If you decrease the time step, it will take longer for the dynamics to develop computationally.

One way to solve this computational problem is to code in a dynamic time step: Keep calculating the $C$ and $C_{max}$. If $C > C_{max}$, then have the model lower the step by half. Check again, then reset for the next step so you can have larger timesteps for "less dynamic" times. I have implemented this many times in other models and it has worked well.

Another possibility might be that you have high aspect ratios in your mesh: if your $x$ direction is 10 km and your $y$ is 1 km, a $10:1$ aspect ratio is very high. In your case, since the model package you use are triangles, you want the angles in the triangle grid to be as acute as possible. Obtuse angles would mean high aspect ration, in general.

Like llmari, I am not familiar with hydrodynamic models, so I do not do specifics. My expertise are in both mantle convection and plate flexure models. I hope this helps.


Is there a way to calculate the ground and 10m temperature from standard 2m temperature measurements?

There is an equation for a model of vertical variation in air temperature

It unifies concepts from a whole range of sciences. You will need to know the sensible heat flux H from the respective surface (which can be calculated as a result of the energy balance of where you are). Further you can calculate the volumetric specific heat capacity pc(p) of air, which is approximately 1.2 kJ/(m³ K) and relate it to the shear velocity or friction velocity of your surface. This is finally related to the logarithmic measure of the term (z-d)/zH where z is the height of which you want to know the temperature and d is the zero plane displacement. zH finally is the Roughness of your surface.

This has to do with the fact, that heat transfer over surfaces usually is turbulent and not just determined by vertical convection. I recommend you to take a look at Campbell & Norman "An Introduction to Environmental Biophysics" (1998). It's a very comprehensive book and treats all the mentioned concepts.

I'm working on a basic computation of this at the moment but it still needs a little time. Once it's done, I'd be very excited to see if it actually is able to model the measured temperatures. I'll keep you updated on how it's going.


Why is the temperature between the earth core and surface not distributed linearly?

The temperature does indeed increase with depth, something that is a problem in deep mines or deep drilling, but a benefit for geotermal heating. The heat originates mostly from radioactive decay, but there is also a fraction of primordial heat from the formation of the Earth.

As a rule of thumb, geologists often assume 25°C/km temperature increasements within continental plates, but steeper increasements in oceanic plates or volcanic regions. The temperature curve is not constant, however. Due to the convection, the temperature increases slower with depth in the mantle and outer core. In that sense, the crust is an isolating cover. The temperature also varies due to subductions, the dynamics of the mantle and radioactivity within the crust.

The shallow soil temperature and the temperature in the air depend mostly on the insolation, the radiation heat from the sun. The average annual solar isolation is 1361 $W/m^2$ but only 20-500 $mW/m^2$ heat flux comes from Earth's internal heat production. However, this tiny fraction can sometime sbe important, e.g. to understand basal melting of ice sheets and glaciers.

Temperature gradient from crust to core. Recent research have improved the accuracy, but the principle in the figure remains (Annual Review of Earth and Planetary Sciences, 24(1), 15–40)

So why do you experience the temperature colder underground when you are digging?

The temperature at depth is the average temperature for day and night or even the year. The energy from the sun reaches only the uppermost soil layer that absorbs heat but the thermal conductivity is relatively low and it will not transport the heat down. The ground is reluctant to change its temperature regardless of variations on the surface.

How strongly you experience the temperature difference depends on where in the world you are and the local conditions. In some areas, the ground remains frozen, known as permafrost, even as the temperatures in the air can be pleasant during the summer and the surface layer melts. The depth of the suggests that it's been formed over a long time. It reaches down to the depth where the mean temperature over hundreds or thousands of years is 0°C. At larger depths, the heat from the Earth's interior takes over and melts the frost.

Temperature in the active layer and permafrost. The thickness of active layer is less than a couple of meters and the thickness of the permafrost depends on its age, the bedrock and the distance to the coast. (By German Wikipedia contributor, "HylgeriaK")

See the plot, linked by @JeopardyTempest in the comments to better understand the variations. Plotted on another scale and depth, annual variations would probably be seen as well.


How older is this snail shell possible could be?

That's not a snail per se it's the shell of an ammonite which is more like a squid with an external shell than anything else I can think to compare it to. They went extinct with the dinosaurs so it's at least 65 million years old and could be much older.


Best way to interpolate bathymetry with a directional component?

I had the same problem with surface DEM's. The best solution I found in Matlab was using the scatteredInterpolant class, it is inbuilt in Matlab. It allows Natural neighbour interpolation (that is a class of weighted distance interpolation as suggested in previous comments). The usage is like this:

% IF X and Y are the coords of each grid cell (you can use meshgrid to get
% those)
invalidValue=NaN; % or -99999 or whatever is in your case
gapIdxs= DEM==invalidValue; %Indexes of the void cells
interpolant = scatteredInterpolant(X(~gapIdxs),Y(~gapIdxs),DEM(~gapIdxs),'natural');
% interpolant is now a function, and we can evaluate it at any point you
% want, in this case we evaluate it in the void cells
interpolatedValues=interpolant(X(gapIdxs),Y(gapIdxs));
% Now we patch the DEM
patchedDEM=DEM;
patchedDEM(gapIdxs)=interpolatedValues;

That produce a result way better than cubic interpolation in my experience. If that is not enough, before you start doing manual picking of features you can explore Kriging interpolation.
Finally if you what to force directionality, you can rotate your data (using matlab imrotate) so that your main direction is vertical and then interpolate column by column (using matlab interp1).


I believe it is not very useful while FDC's  are mostly interesting for the entire discharge record. You can zoom in to the lower part of the curve and analyse it. The problem with the FDC is that it give no indication of sequences of low flows.
You can imagine a river with no discharge (=0) during a couple of months for example. With monthly minimum values this problem is smaller.

In the end I believe it's more useful to use probability distributions for frequency analysis of extreme values like low flows. In literature you can find that the Gumbel distribution of the smallest value is one of the most reliable for annual minimum flows.


Unable to prepare input file for HSPF software for watershed modeling!

I have found the solution and it seems that in BASINS 4.1, user has to import wdm file before launching HSPF by going to 'File' and then to either 'import data' or 'manage data'.  Once this step is done, BASINS 'understands' that there is a wdm file and then the user can add the wdm file from 'met stations' tab.
The tutorials on epa site correspond to BASINS 4.0 and in BASINS 4.0, one doesn't have to go through the so call 'import data' step before launching HSPF.


How did the continental plates came above the oceanic plates?

Too long for a comment, so I'll post here, but it's far from a complete answer.

Basalt can't become continental crust because the elements are different.  Iceland is made up of primarily basalt rock.  (80% per this article).  So it's made up of a different material than continental crusts.   Basalt rock is also less sturdy and less enduring than granite, so it's unlikely that a continental crust could be formed out of Icelandic eruptions or any similar eruptions.   My best guess is that Iceland will break apart over time, preventing the formation of a permanent land-mass.

Granite, the primary material in continental crust, has more Aluminum and Potassium in it.    Basalt, the heavier stuff, has more Magnesium.  Source.    They are made from distinctly separate processes and material, so one can't simply be turned into the other.

While I have no doubt that some mixing goes on within the earth's mantle, I don't believe a significant amount of new continental crust is regularly being formed because to form new crust, you would need free aluminum ready to bind with Oxygen and Silicates and I believe most of the aluminum has already done that.    That's my layman's answer anyway.  I'm open to being corrected.


Are the magnetic elements of meteorites that have struck Earth aligned with the magnetic field?

The surface of 'iron' meteorites certainly gets hot enough to exceed the curie temperature, hence the characteristic ablation texture that you see on meteorites in museums. However, that's a surface feature, and wouldn't affect the interior of all but the smallest of meteorites. The tumbling passage through the atmosphere for just a few seconds, coupled with the shock of impact when it landed is such that there wouldn't be any clear magnetic signature of anything within the outer skin of the meteorite.

In large meteorites, consisting of solid Ni-Fe, the residual magnetism seems to reflect the magnetic field of that part of the solar system from whence they came. Other meteorites contain fragmentary components of varying magnetic orientation, also, (presumably) related to magnetic fields within the early history of the solar system.


How to properly distinguish a transversal valley from a longitudinal valley?

I think that the simplest way is to just look at the map for these two valleys in the Switzerland:
Longitudinal valley:

You can see that this is perfect example on the map: we can easily see the direction of the ridges and the valley is pointed in the same direction. This type of valley was not made by river, but it was made with compressing of tectonic plates.
Transversal valley:

You can see here that some river got through the ridge (then they built the road because the river made all work). It doesn't go parallel ridges like the longitudinal valley. This type of valley requires a lot of work for the river so transversal valley are typically pretty short.


How are 'Morning Glory' clouds maintained?

These are some of the most recent areal photographs taken of this phenomenon. The Morning Glory clouds are the visible manifestation of atmospheric Internal Solitary Waves (see the schematic in (b) below). They propagate on a sharp interface between a relatively dry layer ambient air above and a layer of sea water laden air pushed in from the night before below. When the moist air rises the cloud is formed above the condensation level and eventually evaporates at the trailing edge of the wave.

In these photographs, the cloud itself appears as a cylindrical shaped core with high vorticity at a height of $500$ m and a $1$ km diameter. They may stretch for thousands of kms while traveling at up to $50$ km/h.

Internal Solitary Waves are stable by definition, they are waves of permanent form which owe their existence due to a balance between nonlinear wave-steepening and linear wave dispersion. Of course in the environment there are several other nonlinearities which could potentially break apart this structure through various mechanisms. However, devoid of other atmospheric forcing these waves can travel thousands of KMs without loosing much energy.

A final point is that these waves are ubiquitous but the thing is that we very rarely can observe them is such glorious ways, so there is nothing that says that the Morning Glory is special as far as stability goes compared to other locations on Earth. It is in fact common for such disturbances to maintain their shape over large distances.

Source: Ouazzani, Zaim R., et al. "The Morning Glory: Flow visualization by Mother Nature." Physics of Fluids (1994-present) 26.9 (2014): 091110.


Average thunderstorm days for each month

You should start with NOAA services. They have a Storm Events Database going back to 1950, where you can do queries for states/counties of interest. If you are more interested in lightning data, they also have some products, including raw data from a private company (you'll need access for this) and freely available derived products.


I haven't seen the video you linked to, but from personal experience GPlates is pretty good.  It's open-source and runs on Windows, Linux and MacOS X.


How much water do aquifers contain? How much does it take to deplete them?

It depends on the size of the aquifer and the amount of precipitation falling on the exposed areas of the aquifer. These have been used to provide water form many major cities.
The Trafalgar square fountains were initially powered by artesian pressure (as London is below the altitude of the North downs / Chilterns). Eventully too much water was extracted leading to salt water incursions in places. This aquifer is still in use but backed up by a number of surface reservoirs surrounding the London area.

"
The Report of the Royal Commission on Water Supply (1869) shows that, by 1869, a number of large conurbations were supplied by groundwater. Nottingham and parts of Liverpool and Birkenhead relied on wells in the Permo-Triassic sandstones, Sunderland and South Shields on the Permian Magnesian Limestone and Croydon and parts of south east London on the Chalk. Government offices around Westminster together with the fountains in Trafalgar Square were supplied by wells sunk to the Chalk in 1844 (Amos, 1860).
"

More from here http://www.groundwateruk.org/British-Hydrogeology-a-brief-history.aspx

More detail on the London aquifer:
 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/735451/2018_Final.pdf


What causes smog to clear up on some days?

My guess would be a combination of boundary layer, cloud cover, and emissions (though that isn't terribly specific).

Smog is a combination of nitrogen oxides (which cause smog's brown color), ozone, and particulate matter. These in turn form from emissions of hydrocarbons and nitrogen oxides from vehicles and industrial combustion. If those emissions are lower on some days, the smog's going to be better. But that's a boring answer if you don't have a way of tracking your town's emissions.

Ozone and nitrogen oxides break down and reform in sunlight, driving a number of chemical reactions; this is why smog is usually more of an issue in the daytime. Cloud cover can reduce these sunlight-driven reactions, which can help with smog. Rain washes out most of the particulates, so even light rain overnight can help with smog.

Since the emissions are coming from the ground, they're usually trapped within the boundary layer (https://en.wikipedia.org/wiki/Planetary_boundary_layer). Air within the boundary layer is fairly well-mixed. If the boundary layer is low, then the concentrations are high and the smog is bad. Boundary layers increase in size throughout the day as the ground heats up and convection mixes higher into the atmosphere, so a number of places (including my hometown of Los Angeles) have their worst smog in the morning. How long the smog sticks around depends on how quickly the boundary layer can grow. This depends on a ton of interesting factors -- there are entire textbooks on the subject (The Atmospheric Boundary Layer, An Introduction to Boundary Layer Meteorology) -- but start with the Wikipedia article and let us know if you have more questions about it!


Is Mars' mantle homogeneous or heterogeneous and what might this say about mantle convection?

The mantle of Mars is heterogeneous. While there are many things that are unknown about the Martian mantle and the entire internal structure of Mars, this is not one of them. The source of this finding comes from the analysis of meteorites originating from Mars.

Analysis shows that 4.5 billion years ago - when Mars was forming along with the rest of the solar system - two distinct "reservoirs" formed in the mantle - the "Enriched Reservoir" (ER) and the "Depleted Reservoir" (DR). The ER had high ratios of lanthanum/ytterbium and $^{87}$Sr/$^{86}$Sr, and a low ratio of samarium/neodymium. The DR had the opposite ratios.

Eventually, meteorites known as shergottites formed, mixtures of both of these reservoirs. A graph (which I'd insert here, but I'm unsure of the copyright on it) entitled "Heterogeneous Martian Mantle" illustrates how these meteorites have a wide range of composition compared to rocks from Earth. This provides compelling evidence for a heterogeneous Martian mantle.

At the moment, I can't find enough information to answer the follow-up part, though the convection certainly did stop.

Sources:

PSRD article 1

PSRD article 2


Phosphate in the oceans, does it tend to bond with sodium?

The pH of ocean water is currently about 8.1, which lies between the second and third dissociation constants (7.20 and 12.37, respectively).  So most of the phosphate inthe ocean in its twice-dissociared form, as $\text {HPO}_4^{2-}$.  For comparison, our own blood is around pH 7.4, so phosphate in our blood would be a mixture of $\text {HPO}_4^{2-}$ and $\text {H}_2\text{PO}_4^-$.
In the EPA reference above, it is noted that the slightly lower pH today versus in the relatively past implies a larger increase in hydrogen ion concentration.  But it's worse than that.  Because of the way changing pH is coupled with changing dissociation of acids including phosphoric acid, a seemingly small change in pH could mean a lot more potentially acidic material (in the case of phosphate, $\text {H}_2\text{PO}_4^-$ versus $\text {HPO}_4^{2-}$) in the oceans.


Faults are results of stress. The direction of the stress controls what kind of fault that is formed. The most fundamental reason for a fault to occur is horizontal compression or extension, even if it's often more complicated in reality.

Your two examples are dip-slip faults, with a vertical displacement as a result of horizontal stress.

In your first example, the normal fault. The total distance (from left to right) is increased. There has been an extension of the crust. If the fault plane would have been vertical, no distance would have been gained.

In the second example, the reverse fault, the distance is decreased. It's been a horizontal compression of the crust. The dip of a reverse fault is usually rather steep. If the dip is lower, you'll rather form a ramp. Typical for thrust faults.

Vertical fault planes are associated with strike-slip faults or ring faults above collapsing calderas or sinkholes. It's also common, but not for textbook examples of dip-slip faults.

So, unless you are showing a strike-slip fault, you have to find a way to cut diagonally. Do measure the horizontal displacement!

Addition about making fault models:
We made a layer cake for a college some time ago and (of course) wanted to have a fault in it. The simplest way was to make a reverse fault, erode the uppermost layer of the hanging wall block and assume that the lowest exposed layer was of the same lithology (chocolate sandstone reservoir rock). However, it took some geoenginering to make it look good and we decided to make an impact crater next time.


Complementary to the points about salinity emphasised by TomO and S Verhoef, one more point to emphasise is the role of deep ocean convection. You may have in mind this picture of water sinking because it gets heavy, which is not quite wrong, but you get a more accurate picture if you see that the water column down to about 3000 meter deep is convectively mixing (mainly in winter) in localised areas of the  Greenland, Iceland, Norwegian and Labrador seas. Convection is what you get when dense water lies above lighter fluid, which is as unstable as an egg on its head.

The consequence of this mixing is twofold.

First it shapes the hydrological structure of the deep ocean and determines its organisation into distinct water masses (e.g.: http://www.soes.soton.ac.uk/teaching/courses/oa631/plot_20w.jpg )

Second it induces a strong cooling of the ocean water masses.

Together these effects control the strength of the meridional overturning cell.

If your are after an advanced and authoritative review on this, see http://onlinelibrary.wiley.com/doi/10.1002/2015RG000493/full, which is open access.


Could water pressure at the coast be the cause of continental drift?

Water pressure on both sides of the continent makes sure that all horizontal forces cancel out. So water pressure will not move a continent to the left or right because the pressure on the other side exerts the same force just in the opposite direction (assuming equal water depth). But the water pressure puts the continent under compression and will push the two sides of an ocean apart (putting the oceanic plate underneath under tension). In total, however, these forces are far too small to have any impact on plate tectonics.


Is there a name for the process of producing positional data for cartography?

Surveying is the process of taking topographical measurements of latitude, longitude and elevation. It is also the process of marking out lines for engineering/construction designs of such things as roads, tunnels, fence lines, boundaries & foundations of buildings.

Surveying provides the topographical data that cartographers, engineers and other professionals use for their purposes.


How can the average coldest day of the year be before the winter solstice?

I have created composite plots from reanalysis data for the dates as partitioned in the image in the question.  I used the full NARR dataset, which covers 1979 to 2014, so I have a few more years of data than is included in the image above.

What can be seen are largely wintertime climatological means.  A persistent subtropical high off the California coast and persistent lows in the north Pacific and Atlantic.  What does change is the mean extent of arctic air which descends into the US as winter progresses and retreats as spring approaches.

Composite NARR MSLP and 500-1000 hPa thickness 1979-2014

Figure 1. From left to right, top to bottom the dates composited are Dec 1-15, 16-20, 21-25, 26-31, Jan 1-5, 6-10, 11-15, 16-20, 21-25, 26-31, Feb 1-15, 16-28, Mar 1-15 and 16-31.  MSLP is contoured every 4 hPa.  Thickness is shaded at intervals of 10 dm.  Click the plot for a larger version.

The signal I can pick out of this is the approaching and retreating cold (using the proxy of 1000-500 mb thickness) that seems to correlate well with the latest dates of cold in the eastern US, particularly in the great lakes and northeast.

What I'm seeing in the west is that initially the subtropical high is broad and surface flowing westerlies impinging on the west coast would originate initially at higher latitudes than the do later in the winter.  By January the subtropical high and the low in the north Pacific have re-oriented so the surface flow is coming from around Hawaii.  The western US will also be subject the reduced seasonal temperature fluctuates from its proximity to the Pacific.  Once the area has cooled and equilibrated with the Pacific, temperatures will be stable.  As the continental landmass would lose more energy and cool, the westerlies coming off the Pacific (now relatively warm) counteract this tendency.  Conversely the east with mostly continental air flows experiences large seasonality and has a long-lasted source of very cold air from our neighbors to the north.

Summary

The west ceases to cool once it equilibrates with the Pacific, which looks like it happens early in winter (because even though the Pacific is cold, it isn't that cold).  Westerlies from the ocean heep the west warm.  East of the rockies there is no influence from large bodies of water and a constant source of cold arctic air and so the east continues to cool throughout the winter, until the pattern changes toward spring (and all the snow melts...).

For a smaller scale example of how water can have this influence, take a look at during the next extreme cold event in the midwest and great lakes, particularly when air is flowing westerly across Wisconsin and into Michigan.  You will observe a large temperature gradient across Lake Michigan, which keeps Michigan warmer (sometimes much warmer) than Wisconsin.  Later in the winter when the lake is frozen, that benefit is lost and so Michigan tends to be cooler later in winter as it is no longer "shielded" by the lakes.

Data

Data was downloaded from NOAA's North American Regional Reanalysis, accessed 17 Feb 2015.  Files accessed include:

ftp://ftp.cdc.noaa.gov/Datasets/NARR/Dailies/monolevel/prmsl*nc
ftp://ftp.cdc.noaa.gov/Datasets/NARR/Derived/pressure/hgt.day.ltm.nc


Why do major earthquakes keep happening in Lombok recently?

Yes, it is quite possible to have a number of earthquakes over an extended period of time.

The phenomenon is actually quite common. Some famous sequences are: New Madrid in 1811-1812, Eastern California Shear Zone (1992-1999), Italy (2009-2016), New Zealand (2010-2011) etc. These are all areas where rates of seismicity are relatively low so a number of events in quick succession (as you saw in Lombok) is not due to pure chance.

The idea of one earthquake triggering another on a neighboring or nearby faults is not new.


Why don't spring tides occur at full/new moon (age of tide)?

The age of the tide (a.k.a, age of phase inequality, lunitidal interval) at a location is a term that denotes the interval between the time of a Full or New Moon (when the equilibrium semi-diurnal tide force is maximum), and the time of the local spring tide. In most cases, there is a delay between maximum forces and occurrence of maximum elevation.

The tidal forces generate waves of very long wavelength that travel all around the ocean with a velocity determined by the shallow water progressive wave velocity equation, $c=\sqrt(gH)$, where $H$ is water depth. The delay between the moon phases and their effect on the tide is the time that it takes for the wave to travel around the ocean.

There are two different mechanisms to consider: resonance and friction.

The fact that the age of the tide is analogous to the increase of the phase lag of a forced, linearly damped harmonic oscillator as the frequency increases was known since the XIX century. The damped oscillator analogy does not explain the phase magnitudes in the real ocean.

The inclusion of friction is necessary to explain the observed time lags. Proudman (1941) showed that by including frictional effects on coastal areas, a positive age of tide appear in the tidal solution. If there is some resonant frequency in an ocean basin close to the semi-diurnal frequencies ($M_2$, $S_2$...), friction enhances the age of the tide resulting in higher delay values. Garrett & Munk (1971) and Webb (1973) provided a methodology for the calculation and estimates around the oceans. The longest delays (longer than 60 hours) were estimated in areas with the largest continental shelf, as they represent areas of strong tidal dissipation: the North Sea, the Ross Sea, Hudson Strait, the shelf off Argentina, the Bering Sea, and the Sea of Okhotsk.

The age of tide can be obtained from the harmonic constants by dividing the difference in phases of the $S_2$ and $M_2$ constituents by frequency separation between both constituents:
$ Age\_of\_tide = {Phase\_of\_M_2 - Phase\_of\_S_2 \over 1.0163 }$, where the phases are measured in degrees and the age of tide is in hours.


How are biological oxygen demand and depth related?

Biological Oxygen demand increases with accumulation of decaying organic matter in a water system. This means that BOD is highest where there is high concentration of decomposing organic matter in that system.

  What is the relation between biological oxygen demand (BOD) and depth?

The answer may vary as in some cases organic matter floats on upper columns of water and can be decomposed readily by aerobic microorganisms manifesting an increased BOD.

However, this study   which was conducted using waste water from stabilization ponds (depths ranging from 0-5m) shows that there is an increase in the Biological Oxygen Demand with increasing depth and this can be attributed to the settling down of organic matter in these ponds.


Why is CO2 considered a greenhouse gas? Can you explain the principles?

Yes, you are right, the title says it all. The presence of greenhouse gases, of which there are several, allows radiant energy from the sun to pass through the atmosphere but hinders the longer wavelength, infra red, thermal radiation from getting back out again, thus acting like the glass in a greenhouse. CO2 is a less effective greenhouse gas than methane, but there is much more of it in the atmosphere and it stays there longer, so this is the one which causes most concern. There are natural processes which reduce the amount of CO2 and methane in the atmosphere as long as the input, mainly from human activity, is not more than they can deal with.


Calculate flow rate of wetland for gray water treatment

What you're really looking at is a fairly basic groundwater flow problem. What you need are hydraulic conductivity values for the "gravel" sediment in question. Given the fixed 1% grade, what you want to find is the "tank" length that maximizes pollutant residence time, and is relatively easy to calculate.

I believe that this is the basic design around which your illustration comes from:

Horizontal Subsurface Flow CW

I don't know how you're going to solve the problem of finding and keeping enough water in your system during the dry season. You're system depends on growing plants!


Why is heavy precipitation from atmospheric rivers more likely to hit the West Coasts than the East Coasts?

Extratropical cyclones in the Northern Hemisphere rotate around the earth in the mid-latitudes in a mean westerly flow.  This means that, on average, the track of a storm between 30°-60°N moves from west to east.  Ahead of these extratropical cyclones is a strong frontal boundary with very powerful winds, sometimes up to hurricane strength near the boundary layer.  Moisture is advected (transported by wind) from the tropics (a very wet place, relatively speaking) by these powerful winds ahead of the extratropical cyclone. The moisture then creates a narrow channel of extremely moist air along the frontal boundary. Finally, the atmospheric river moves with the mean westerly flow as the frontal boundary/extratropical cyclone shifts east. Therefore, to answer your question, it is because extratropical cyclones on average move from west to east that ARs impact west coasts in the Northern Hemisphere.

Atmospheric River preceding Upper low in Mid-latitudes off of US West Coast

Another way to think of this is that tropical systems (those that develop between 0°-30°N) initially move from east to west in the easterlies.  Now ask yourself how often do the mid-latitude west coast's of northern hemisphere continents fall victim to category 3-4-5 hurricanes?  Caveat: remnants from weakening tropical depressions often move into the mid-latitudes before impacting these regions.

Track of tropical cyclones in the opposite direction of Atmospheric Rivers


Take a look at the RSAGA package on CRAN, or the rgdal package. Many of the GIS methods can be done in R but basically act as a wrapper for saga or gdal. RSAGA is likely your best bet for processing terrains for flow analysis.

I also know of Dan Moore from UBC who does a lot of work with R and GIS applications, worth taking a look there and certainly those algorithms can be done in R directly.

There is also another post in the GIS forum on using TauDEM in R, worth taking a look as well. TauDEM in R - additional SO post

In general, rseek is an excellent search engine for exactly this type of problem in case you don't find what you are looking for in those links above.

For actual flood routing, you may be interested in the Height Above Nearest Drainage Model (HAND), which uses the same type of D8 flow accumulation algorithm to build a rapid method for floodplain mapping. Good paper on that some other 1D methods.


Why does the "Ring of Fire" pretty much define "Pacific Rim"

There isn't a concentration of tectonic plates - rather the opposite!

The "Ring of Fire" is a pattern really. It is marked by subduction zones. So the question becomes, "Why is the Pacific Ocean surrounded by subduction zones?".

Think back to Pangaea. This was a supercontinent that formed in the late Palaeozoic. Virtually all of the Earth's land masses were concentrated in one large supercontinent. When this broke up, the new continents moved away from each other. Fast forward 200Ma or so, and you find that the continents have moved so far apart that they are now converging on a point on the other side of the planet - the continents are moving towards each other! Hence the remains of the super ocean (which was actually multiple ocean plates - today's Pacific & Nazca plates, plus the Farrallon plate (RIP),etc ) is shrinking as the continental plates move towards it.
This destruction of the ocean plate(s) occurs at subduction zones.

This is a big picture generalisation. Not all of the Pacific's boundaries are marked with subduction zones (e.g. North America has two large strike slip systems + a new spreading ridge). Also, not all of the continents are converging on each other. Africa is doing a pirouette, India is moving northwards, etc.


What is it called for the part of a hill where it discontinuously gets steeper?

As far as I am aware there is no single term to describe the sudden change in the gradient of a slope. Personally I would describe it simply as a sudden increase in slope. However there are many words to describe the landforms that occur when gradient sharply increase.

Terms such as cliff, escarpment and mountainside all describe the steep landform as whole. Whereas terms such as flank or face describe the side of the hill only with a steep gradient.

You might find this link particularly helpful:
https://www.macmillandictionary.com/thesaurus-category/british/parts-and-features-of-mountains-hills-and-cliffs


Yes, it is possible. The documentation for Hydrus-3D give you the syntax (http://www.pc-progress.com/en/OnlineHelp/HYDRUS3/Hydrus.html?RunningComputationalModulesinaBa.html)
In brief here is what you need to do:

In the installation folder of Hydrus, create a text file, name it run.bat
You need to write two lines of code for every  simulation you wish to perform:

copy path1 level_01.dir      (here path1 can be replace what what ever name you want)
h2d_calc                     (this is the executable so depending on the type of model you want to run you may have to adjust the name)

In the installation folder of Hydrus create a text file and name it path1 (or whatever name you wrote in step 2), do not forget to remove the .txt extension for the case display here)
In the path1 file, write the path to your input files
for example: c:\program files\ussl\hydrus3d\mydirect\run1

Then double clicking on the bat file will trigger the model to run. By adding successive copy ... and h2d_calc commands you can chain model execution

In addition some tricks are available here: https://www.pc-progress.com/forum/viewtopic.php?f=4&t=679


Does the Great Pacific Garbage Patch increase sedimentation rates over the patch?

This is somewhat a partial answer, as there is still a considerable amount of research being performed on the effects of the Garbage Patch.  The focus of this nswer will concentrate on what the US EPA (3) identifies as being the pollutant that contributes 96% of the Garbage Patches in the north Pacific - 'microplastics', pellets less than 5 mm in size.

According to Rios et al. 2010 (1), the plastic in the North Pacific Gyre are found to function as "a solid-phase extraction media" causing adsorption and concentration of pollutants out of the water column, similar to what has been found for marine sediments.

However, microplastics are found to be what Rios et al. (1) describe as being "inverse sediments" in that they do the opposite of natural marine sediments and remain floating on or near the ocean surface. Zarfi et al. 2011 (2) observed that microplastics can be incorporated into the natural sediments, and potentially wash up on beaches (e.g. if caught in a coastal current as seen n the diagram below) etc - whether or not, being incorporated into these natural sedimentation processes provides a 'sink' for the microplastics is still unclear (2).

References

(1) Rios et al. 2010, Quantitation of persistent organic pollutants adsorbed on plastic debris
from the Northern Pacific Gyre’s ‘‘eastern garbage patch’’, Journal of
Environmental
Monitoring

(2) Zarfi et al. 2011, Microplastics in oceans, Marine Pollution Bulletin

(3) US EPA, 2011, Marine Debris in the North Pacific, U.S. Environmental Protection Agency


Can someone help me identify this cloud formation?

Well, after a bit of research, I stumbled upon the following image:

This is from a blog of two storm chasers Roger and Elke who I believe witnessed the same cloud formation as you. In the following link:

http://stormeyes.org/latest/tag/left-moving-supercell/

They refer to the formation as a 'rear flank arc cloud'.

So in conclusion I believe, the formation is a kind of arcus cloud. You can learn more about arcus clouds on wikipedia by following the link:

https://en.wikipedia.org/wiki/Arcus_cloud

I hope I have been of help.


The major factors in temperature change from precipitation...

First, fundamentally rain is falling to the ground from higher in the sky.

Precipitation typically comes from a location where it is colder compared to us on the ground (the troposphere generally is cooler with height, on average around 6.5 Celsius\km.).
Basically, the rain itself usually at least feels colder than the air beforehand, right??

Well, if you do bring something colder to a warmer environment, their temperatures will tend to move towards a balance between the two.
[++ see Second Law of Thermodynamics ++]

So with significant rainfalls, there's a lot of cold water being spread down into our warmer air, and due the dispersed nature of rain (a bunch of small drops rather than one giant stream) it ensures that rain is quite quick and effective in spreading it's cold temperatures into the air.

Second, falling rain also encourages downward air movement, due to friction.
[++ see downdrafts ++]

So not only is rain (that is almost always colder) coming down, but air (that is almost always colder) is coming down too.

Furthermore, rain is cooling the air it is falling through, colder air sinks, so the downdraft is further enhanced.
[++ Actually the air must be quite a bit cooler to sink on its own... see adiabatic warming ++]

So this is a second fairly quick cooling process, as downdrafts occur within the lifecycle of a thunderstorm cell/complex.

And third, some of the rain/snow/sleet/hail/etc water will begin to evaporate (or sublimate!) as it is falling and once it reaches the ground, unless the air is totally saturated.  When water evaporates, it needs to gain energy.  To do so, it takes energy from the environment, namely the air.

This evaporative cooling just exacerbates the first two influences above.  And furthermore can continue to have impacts days after the rainfall compared to drier places, stunting high temperature ascension during the afternoon.

[There are also other factors important in the longer term, such as snow reflecting sunlight (cooling the area), moister air being favored for cloud formation (which cools during the day, warms at night), and the fact moister air changes temperature at a slower rate due to its heat capacity (cooling during the day, warming at night).]

But, the result is, scientifically, when precipitation falls, it is fundamentally a cooling process.
The stronger the precipitation is, the much more significant the cooling.  And certain atmospheric setups enhance the cooling effect even more (steep lapse rates, dry air nearer the ground)

Now, even after saying all that, it actually can still be warmer soon after rainfall.

How in the world is that possible!?!
Because wind can still blow in large amounts of air from other areas... sometimes from environments that haven't yet themselves experienced significant precipitation.
This often happens as warm fronts pass.

[++ Heaviest rainfalls do more often come with cold fronts, which bring in more cold air.  However most (nontropical) lows start with a balance of areas of advancing warm air followed by surging cold air.  So you may well see both... or you may not: in more mature storm systems - as you'll often see in winter - most warm air is completely undercut by cold air... and so many large areas never experience any notable warmup as a storm system works through ++]

Other unbalanced factors can overwhelm the cooling effect as well... like when it's cloud all day, then rains a bit, but finally the sun comes out.  The hot sun can quickly turn the battle back towards the warmer side.

[++ There is indeed at least one other very very rare way, where if the atmosphere is setup perfectly, a strong downdraft can actually begin to warm due to adiabatic compression, but still have enough oomph to reach the ground... and you wind up with a heat burst. ++]

So air after rainfall is cooled in the extreme majority of cases... it's just that your cooled air may instead end up being relocated to other locations.

Check out the topic of outflow boundaries

So, to your questions:

⇒ Will it be colder right after a storm compared to how it was
   right before the storm?
   Most likely

⇒ Will it be colder the day after a storm compared to how it was right before the storm?
   Depends what the weather pattern and air mass movement is like.  If a cold front moves in, yes.  If a warm front moves in, no.  In the tropics or during the height of summer, it will often be about the same the next day as the atmosphere mixes the cool air from yesterday's rain around until it's spread out and minimized, and the air heats back up again the next day when the sun comes out.

⇒ Will it be colder after a storm than it otherwise would have been without the storm?
  Basically yes.  A nearby site that doesn't get the storm's effects will almost certainly be warmer.


Would the enthalpy of fusion for melting ice fields be a causative factor for colder winter weather?

No, for a number of reasons.

Ice sheets melt in the summer and rebuild in the winter. This is winter.
The enthalpy of fusion for water is 333.55 joules per gram. Multiply that by 280 gigatons per year and you get 9.3×1016 joules per year. While that sounds like a lot, it's a blip compared to the 5.5×1024 joules the Earth receives from the Sun every year.
It's not a cold winter. While it has been an abnormally cold winter for the eastern parts of the U.S. and Canada, the rest of the northern hemisphere has been rather balmy. Nuuk, Greenland, for example, is suffering a heat wave. The current (06:38 UTC 21 January 2018) temperature there is 3°C (37° F), significantly warmer than average. The normal high for that location at this time of year is -6°C (24° F).

The melting of all that ice might well have an impact on climate, but it's the influx of 280 gigatons (and rising) of fresh water every year into the northern ocean rather than a paltry absorption of 1017 joules of energy every year that will be the cause.


Why do values stored in data files, such as climate model output, appear to be high?

My professor gives the solution, as we can see at the site were the climatic variables came from http://www.worldclim.org/formats1:

  Please note that the temperature data are in °C * 10. This means that a value of 231 represents 23.1 °C. This does lead to some confusion, but it allows for much reduced file sizes which is important as for many downloading large files remains difficult. The unit used for the precipitation data is mm (millimeter).

(Edited in by Gerrit): storing (climate) data with offsets and scale factors to reduce file size is common practice, as scaled integers can easily be less than half the size of floats.  When data are stored in standard formats sch as NetCDF or HDF-5, there is probably a variable attribute documenting this.  When data are stored in a homegrown format, check the documentation carefully for any mention of offsets and scale factors that need to be applied.


Shouldn't we encourage consumption of single-use plastics? Plastic is a good way to sequester carbon

Plastic isn't a good way to sequester carbon the sense that this term is usually meant.

Carbon sequestration is normally assumed to mean

  [...] the long-term removal, capture or sequestration of carbon dioxide from the atmosphere to slow or reverse atmospheric CO2 pollution and to mitigate or reverse global warming.

(From Wikipedia, my emphasis.)

This is not how plastic production works: the great majority of plastic is made from petrochemicals.  So almost all plastic is made from fossil carbon, not from carbon extracted from the atmosphere recently.

With plausible assumptions about the energy used in making plastic and its source, then turning fossil carbon into plastic which is then not burnt is probably better in terms of carbon emissions than just putting the fossil carbon straight into the atmosphere.  But it's worse (again in terms of carbon emissions) than just not making the plastic at all.

Note that there have been plastics made from plant materials, and many early plastics were made like that: Celluloid is a good example.  I thought Bakelite was as well, but it turns out it's the first one that wasn't.


What is responsible for the underwater waterfall illusion of Mauritius Island?

The cause for this phenomenon is sand and silt moving down an underwater cliff as you guessed.  The geography that makes this possible is as follows.  The island of Mauritius is located on a giant plateau that was created by seafloor spreading a few million years ago.  Most of which is under 8-150 meters of water.  Where the waterfall effect occurs there is a huge drop-off which drops down thousands of meters.  Because of the islands angle when the waves beat upon the shore and displace sand, the drawing out of the waves creates, you could say, a down pulling  effect.  This motion pulls the sand and silt down the drop-off, thus creating the underwater waterfall illusion.  Because waves constantly bring sand and weathering and erosion keep making sand and silt, is not very probable that this illusion will stop for a long time, if it stop at all.  I hope this was helpful.


Are metals and other elements in every continent?

Metals occur on every continent . The issue is whether or not they occur in sufficiently large deposits for them to be mined economically.
The difference between a mineral deposit and an ore body is economics: can it be mined for a profit?
One of the issues with mineral resources is that once they've been mined, they're gone.
Cornwall and Devon, in the UK, were once a significant producer of tin and copper.
Spain is major source of metals in Europe. Some of its mines were started by the ancient Romans. Poland too, has a active mining industry, as does Sweden.
Chile and Peru are major sources of copper, but copper is also mined in the US, Zambia, Australia and Russia.
Africa has a well established mining industry that mines many metals: gold, copper, iron, lead, zinc and platinum.
Metal mining in Australia and Canada provide both countries with significant sources of export income.
China has iron ore deposits that grade between 25 and 40 percent iron, but it prefers to buy higher grade iron ore, grading 65 to 70 percent iron, from elsewhere, mostly from Brazil, Australia and South Africa, because it is cheaper to produce steel from higher grade ore.
However, mineable quantities of some metals, such as lithium, platinum and rare earth metals tend to be concentrated in specific locations.


How are critical loads of nitrogen deposition on eco-regions determined?

These two links were the sources I used when researching this question:

"Mapping critical loads of nitrogen deposition for aquatic ecosystems in the Rocky Mountains"

http://co.water.usgs.gov/publications/non-usgs/Nanus_2012.pdf

"Approaches for estimating critical loads of nitrogen and sulfur deposition for Forest Ecosystems of U.S. Federal Lands"

http://www.nrs.fs.fed.us/pubs/gtr/gtr_nrs71.pdf

It looks like there are actually several different approaches which can be used when calculating the Critical loads, and depending on the approach the factors considered change:

Empirical (Regression) modeling: These are generally based on observations of ecosystem response (this is tracked off of Foliage, lichens, or soils) and tracked to a given deposition level. This is generally calculated in one area, and applied elsewhere.
Simple mass-balance models: estimating a net loss or accumulation of nutrients based in the in/out of a system for that nutrient. These are basically steady state models and are measured generally on base cations or nitrogen.
Dynamic models using a mass balance approach which incorporates internal feedbacks over time. This is a combination of the two and is generally used where there is an abundance of existing data.

The links contain further information which may be more helpful.

According to "Wolfe, A.P., Baron, J.S., Cornett, R., 2001. Anthropogenic nitrogen deposition induces rapid change in alpine lakes of the Colorado Front Range (USA). Journal of Paleolimnology 25, 1e7." as cited in the first article I linked, This excess N (caused by exceeding the critical load) can result in acidification and nutrient enrichment, increasing primary productivity in high-elevation lakes and streams, and altering diatom community structures that form the base of the food web –

The USFWS Ecoregion classification system was designed by Robert G. Bailey working out of the Rocky Mountain Research Station in Colorado. In his paper, "Identifying Ecoregion Boundaries" found Here: http://www.fs.fed.us/rm/ecoregions/docs/publications/identifying-ecoregion-boundaries.pdf  he outlines the rational used for identifying the boundaries, and the 20 different principals he used. They are: 1. The series of ecoregions should express the changing nature of the climate over large areas. 2. Boundaries of ecoregions coincide with certain climatic parameters, 3. , 4. , 5 - 20


What methods exist for remote profiling of oceanic columns?

There are a number of programs and instruments that sample the ocean autonomously. Examples of such programs are:

The ARGO program (http://www.argo.net/): Currently around 3000 floats are freely drifting in the ocean measuring temperature, salinity and in some cases velocity of the upper 1000-2000 meters of the ocean. The floats drift for around 10 days most commonly at 1000 or 2000 meters and then conduct a vertical profile to the surface where they transfer the data to a satellite.
RAFOS floats (http://www.whoi.edu/instruments/viewInstrument.do?id=1061): They map the ocean currents using the SOFAR channel (a horizontal layer in the ocean where sound speed is minimum).
Gliders (http://www.ioos.noaa.gov/glider/): A type of autonomous underwater vehicle (AUV) that uses buoyancy to control its vertical position in the ocean. They sample along predetermined routes and can be equipped with instruments to measure temperature, salinity, turbidity, velocity...
Other AUVs: Most other AUVs use propellers powered by rechargeable batteries and are able to carry a lot more instruments, but are limited to shorter missions.

Measuring oceanographic interior conditions remotely is much more challenging. While satellites provide data for sea surface (or near-surface) parameters, such as temperature (e.g., MODIS), salinity (SMOS & Aquarius), height (e.g., Jason 2) and color (SeaWiFS, MODIS), remote interior data are more challenging to acquire.

Seismic oceanography is a recently developed technique that uses multichannel seismic reflection to characterize the ocean interior. It provides continuous mapping of the finer structure associated with the thermohaline (temperature and salinity) structure of the ocean. One of the best examples is Holbrook et al., 2003 Science paper (sciencemag.org/content/301/5634/821.full). You can find more information in: steveholbrook.com/research/seismic_oceanography and www.utm.csic.es/so


What is the potential impact of hurricane intensification and sea level rise on coastal flooding?

As you noted, the (predictions about) impacts of global climate change are region specific. The general reasoning behind predictions for many regions are similar however, as are some noteworthy bottom lines (such as increased exposure to flooding as your question focuses on), so I'll try to summarize those from rich and reliable sources.

The Maryland Sea Grant website states on its Storm Surges page:

  As sea level rises, flooding due to storms will worsen so that homes and buildings already vulnerable to storm surges will sustain more damage. Powerful storms can damage dwellings or flood low-lying areas with high tides and wind-driven waves. Some Maryland neighborhoods could be underwater completely.

  ...

  A special report, Come High Water: Sea Level Rise and Chesapeake Bay, offers a comprehensive look at the causes and consequences of increasing flooding along Maryland’s coasts. This package, produced by Maryland Sea Grant's magazine Chesapeake Quarterly in partnership with Bay Journal, examines the scientific understanding and projections of the rate of sea level rise in the Chesapeake region; effects on people and the environment; and adaptations and policy responses that are under way or under consideration. An online interactive page offers videos, photos, and an interactive map showing flooding that is predicted to occur.

The PDF of "Come High Water: Sea Level Rise and Chesapeake Bay" has more detailed explanations, data, and citations, and is available from that page.

On its Rising Sea Level page:

  Scientists have forecasted an increase of as much as 2.1 feet in the Chesapeake Bay by 2050. And by the end of this century, that number could be 3.7 feet or higher. Scientists have identified several reasons, which are described in a video produced by Maryland Sea Grant (below):

  As oceans around the world grow hotter, they also expand because of the chemistry of salt water.
  Glaciers and ice caps, including the icy regions around Greenland, are melting.
  Since the end of the last ice age, the land around Maryland has been naturally sinking a tiny bit each year — a trend that has accelerated over recent decades.

That article linked to where the above quote says "Scientists have forecasted..." has a worthwhile introduction to answer your question and provide context to the source:

  State Should Consider Longevity of Structures Built Near Water, Report Says

  Maryland residents should plan for the state’s coastal waters to rise by 2.1 feet by the year 2050 and by 3.7 feet or more by the century’s end, according to a new analysis by scientific experts prepared for Gov. Martin O’Malley. The panel reviewed recent evidence about sea level rise in Maryland and globally.

Based on your asking about specific studies that quantify these [climate change] effects: if you are interested in more detailed data and prediction methods, you can easily find various climate forecasting models if you search for them. One example is NARCCAP. It and many other climate forecasting models are public-domain but fairly technical. Another example is https://www.data.gov/climate/coastalflooding/

Many climate change impacts are predicted based on environmental models and the data sets they produce. For a glimpse at modeling efforts very relevant to your question, you could explore these papers:

DesAutels, 2000. Upper-Ocean Influences on Hurricane Intensification
Modeling.
Hellegatte et al, 2010. Assessing climate change impacts, sea level rise and storm surge risk in port cities: a case study on Copenhagen.
Mousavi et al, 2009. Global warming and hurricanes: the potential impact of hurricane intensification and sea level rise on coastal flooding.
NCAR Article: Evaluating the Effects of Future Sea Level Rise and Storm Surges Along U.S. Coastlines and associated paper: Tebaldi et al, 2012. Modeling sea level rise impacts on storm surges along US coasts. Both of these support and address your question in the first place.

The Hellegatte et al, 2010 paper is focused on economic analysis which you may be interested in:

  For  instance,  the  total  losses  (direct  and  indirect)  caused
  by  a  present-day  100-year  storm  surge  event,  at  150  cm  above  normal  sea  level,
  are estimated to reach EUR 3 billion with no protection. In the aftermath of such
  an event, thousands of jobs would be lost and thousands would be created in the
  construction  sector.  Other  types  of  impact  have  been  disregarded  here,  but  may
  also be important (e.g., casualties, illness, psychological trauma, disruption of social
  networks, loss of national competitive strength and market positions, loss of cultural
  heritage, city attractiveness, etc.). Even with the relatively narrow set of economic
  impacts  considered  here,  the  reconstruction  process  would  last  several  years  and
  cause a significant shock to the local and the national economy.

The Mousavi et al, 2009 paper provides specific predicted sea level rise quantities which may be more what you are after:

  For  the  Corpus  Christi,  Texas,
  United  States  study  region,  mean  projections  indicate  hurricane  flood  elevation
  (meteorologically  generated  storm  surge  plus  sea  level  rise)  will,  on  average,  rise
  by 0.3 m by the 2030s and by 0.8 m by the 2080s. For catastrophic-type hurricane
  surge events, flood elevations are projected to rise by as much as 0.5 m and 1.8 m by the 2030s and 2080s, respectively.

Again there are many modeling/prediction and analysis efforts and varying scenarios for different regions. If you were more specific about the region and particular analysis you're interested in, folks could probably share more specific answers.

TL;DR: Sea level is predicted to rise due to climate change, to varying extents place-to-place, and that rise in sea level will increase the magnitude of damage many places are exposed to due to storms, which are also predicted to pose a more significant threat due to increased intensity and frequency.


Plotting wind barbs in python (no U,V component)

I can answer this in two steps

Calculate $u$ and $v$. This site has formulas for $u$ and $v$. They are as follows: $$u=-|\vec{v}|\sin(\frac{\pi}{180}\phi)$$ and $$v=-|\vec{v}|\cos(\frac{\pi}{180}\phi)$$
where $\phi$ is the wind direction in the meteorological system, and $|\vec{v}|$ is the wind speed.
Having calculated $u$ and $v$, you can plot the wind barbs by following the example found at this site.


Why exactly is the feature on Io called a volcano, and the feature on Enceladus called a geyser?

The difference between a volcano and a geyser is defined by what is being ejected.

Volcanoes eject lava, which is molten rock. Molten rock that stays underground is called magma, but when it reaches the surface, usually via a volcano, it is called lava.

A rock is composed of minerals, such as sulphides and silicates. The volcanoes on Io eject lava that is "composed of various forms of elemental sulfur. The colouration of the flows was found to be similar to its various allotropes".

Some volcanoes on Earth also eject elemental sulfur, such as Mount Ijen in Indonesia.

Geysers on Earth typically eject water or steam. But elsewhere in the solar system cryogeysers exist; they eject "volatiles, together with entrained dust or ice particles, without liquid".

On Enceladus, the geysers eject water, ice particles "and smaller amounts of other components (such as carbon dioxide, nitrogen, ammonia, hydrocarbons and silicates)". Unlike in lava from volcanoes, the silicates ejected from geysers on Enceladus are a minor component of the ejected material.

In addition to volcanoes and geysers, there are cryovolcanoes, also known as ice volcanoes, on some bodies in the solar system. Like geysers, they eject volatiles "such as water, ammonia or methane, instead of molten rock. Collectively referred to as cryomagma, cryolava or ice-volcanic melt, these substances are usually liquids and can form plumes, but can also be in vapour form. After eruption, cryomagma is expected to condense to a solid form when exposed to the very low surrounding temperature."


Nuclear testing and the Anthropocene, a chemostratigraphic link?

Certain anthropogenic radionuclides have pragmatic advantages as markers for the start of the anthropocene.  The advantage of radionuclides over anthropogenic stable nuclides is that the primordial production of all but a few radionuclides has decayed away.  Thus natural background levels are below detection by sensitive analytical methods except in a few localized situations (e.g. preCambrian natural reactors). Even radionuclides that occur naturally may be useful if the anthropogenic signal is much greater than the natural levels.

An important trait for a radionuclide stratigraphic marker is that it has a long enough half-life so the anthropogenic material remains in the sediments.

The other important trait for a stratigraphic marker is that it is not redistributed significantly in the environment and stays with the sediments of the proper age. For this reason, 137Cs and plutonium isotopes are valuable since they have low solubility/strong adsorption onto sediments and were distributed widely by atmospheric nuclear testing. However, this does not mean that the radionuclides won't be redistributed. The radionuclides can be redistributed by water, wind, or mass wasting. Colloidal transport can move particles even in saturated groundwater and the vadose zone. In fact, levels of atmospheric fallout plutonium have been used to interpret the redistribution of other contaminants.

Even with very low solubility there can be some dissolved transport into earlier or later sediments. For example, Woods Hole Oceanographic Institute has determined that plutonium mobility may be affected by oxidation state and that more mobile 244Cm can be transported before it decays to 240Pu.

Thus, anthropogenic radionuclides, particularly those of long half life and low solubility that were produced during atmospheric testing, have properties that make for pretty good stratigraphic markers. But the limitations should be kept in mind.

An additional problem is in defining the 'start' of the anthropocene as fitting your marker rather than the other way around.  Certainly, people have had had geologic and ecological impacts before 1945. There are indications that aboriginal burning regimes over 20,000 years caused nutrient export with effects that can be seen in current groundwater chemistry.


How much change has there been to the shape of plate boundaries over geological time?

I am not sure if you are actually asking about Tectonic Plate boundaries, or the boundaries of continents, which are often described a puzzle pieces when teaching continental drift due to the way continents like South America and Africa fit together. I'm going to try and address both possibilities.

Tectonic Plate boundaries are constantly changing. Many of the edges of tectonic boundaries are thin freshly-formed oceanic crust which isn't going to put up much of a fight. You know about subduction so you understand that oceanic crust is constantly 'recycled'.

The present day amount of continental crust on earth hasn't existed for all of earth's history. Current thinking is that it has been been accumulated overtime (theories differ as to how quickly), through a number of processes which have built up the present level of continental crust that is more buoyant that the mantel and oceanic crust and thus resistant to subduction. As a result the size and shape of the continents have been slowly changing and growing over earth's history as they gain new bits, join and split.

  For example, what would the 'jigsaw pattern' of plates at the time of Pangea have looked like?

this video shows continents moving around, growing and joining and how they change over time, at least for the last 1.5 billion years of earth's 4.5 billion history. Pangea was around from 335Ma to 175Ma, you can see it form and break up in the video.

https://www.youtube.com/watch?v=IlnwyAbczog

  This probably relates to the potential for new plate boundaries to be
  formed...and existing ones to close up. Is this possible?

In this video blue and red lines show active tectonic plate boundaries.
you can see that they change. They move around, old ones stop and new ones start. They even change from divergent to convergent or consume each other.

  At plate margins, does the pressure of compression or expansion actually change the spatial position of the margin?

Absolutely. at the end of the video watch India slam into Asia and create the Himalayas as a result.

I'm not an education specialist, but i have seen videos like these be used to explain the processes to kids.


Yes, in your example, the group should have been omitted. From the WMO Publication No. 306 - Manual On Codes - Volume I.1 - Part A, Section A, FM 12 SYNOP:

  12.2.7 Group 8NhCLCMCH

  12.2.7.1 This group shall be omitted in the following cases:

  (a) When there are no clouds (N = 0);

  (b) When the sky is obscured by fog and/or other meteorological phenomena (N = 9);

  (c) When the cloud cover is indiscernible for reasons other than (b) above, or observation is not made (N = /).

metaf2xml tries to stick to the Manual but tolerates deviations, so the group is recognized but marked as invalid.


How will climate change affect the 3D distribution of lapse rate in the atmosphere?

Stone and Carlson, 1978 suggest that lapse rate is dependent on latitude (i.e. incidence angle and intensity of sunlight) and pressure rather than temperature. It is the sunlight pattern which drives the circulation patterns that are the dominant effect of air temperature with altitude:

  In low latitudes where moist convection dominates, the lapse rate agrees
  closely with the moist adiabatic lapse rate; and in high latitudes where
  baroclinic eddies dominate, the lapse rate agrees closely with the
  critical lapse rate for baroclinic adjustment.

The latitude determines daily changes in temperature due to solar energy. This leads me to believe that changes in average temperature (due to climate change) will not affect lapse rate so much as solar incidence due to latitude (which will not change with global warming). However, there remains the potential effect of increased humidity caused by increased temperatures.

An analysis of lapse rate measurements over broken terrain in Washington state (Minder, Mote, Lundquist, 2010) shows the differences between wetter and dryer conditions on the windward and leeward sides of Mt. Ranier. A calculation of lapse rate up the mountain by season yields this chart:

There are three distinct data sets: the solid black is the same on both a. and b. and is the measurements in 2006-2007 of lapse rate by month. The grey with circles data set from a. and grey with triangles from b. are two historical data sets from different sources. The dashed lines in each data set are on the leeward (dry) side of the mountain, the solid lies on the windward (wet).

As you can see, the seasonal variance is present in all three datasets; as the sun comes more nearly overhead in the summer lapse rate goes up. Also notice that for the leeward data, the lapse rate peaks in Jun, when the sun is highest in the sky, as opposed to July and August, when temperatures are high. That reinforces the thesis that sun angle is dominant over temperature.

However, the other bit of relevant data is that the wet side of the mountains has significantly less annual variability in lapse rate than the dry side. This implies that humidity changes due to global warming will indeed cause changes in lapse rate.

In conclusion, I believe that temperature changes due to climate change will not significantly alter lapse rate; but humidity changes will. However, since humidity changes due to climate change are likely to be much more local and variable than the more globally even increases in temperature, lapse rate changes should be local and variable as well.

So to answer the question directly, the '3D' changes in lapse rate will probably not be significant, in that there will not be a clear global trend across all latitudes, longitudes, and altitudes. However, local changes may be significant depending on local humidity changes.


How would weather change on a tidally-locked terrestrial planet?

My best estimate on what would happen is the following:
 - At the twilight zone there would be tremendously fierce and constant windstorms as the heavier cold air rushed from the dark side to displace the lighter air warmed by the Sun.
 - Additionally, the wind patterns would generally align themselves towards and away from the twilight zone.
 - Over a millennia, the storms would probably carve canyons and deep scars into the face of the planet along the twilight zone.
 - Relative calm would be found in the area closest to the Sun as well as farthest from the Sun.
 - If the planet were inhabited, the inhabitant would probably be locked to either the light side or the dark side unless they had some method of navigating through or around the storms.
 - I don't know if it would rain or not, but if it did, it would definitely only rain on the side facing the Sun, as the other side would be perpetually frozen.

I'm not a meteorologist, this is just a thought exercise, so I don't know how accurate any of this is (although I do have some basic knowledge of meteorology).

EDIT: I found this wikipedia article, which seems to support my theories.

  Due to differential heating, it was argued, a tidally locked planet would experience fierce winds blowing continually towards the night side[citation needed] with permanent torrential rain at the point directly facing the local star, the subsolar point. In the opinion of one author this makes complex life improbable. Plant life would have to adapt to the constant gale, for example by anchoring securely into the soil and sprouting long flexible leaves that do not snap. Animals would rely on infrared vision, as signaling by calls or scents would be difficult over the din of the planet-wide gale. Underwater life would, however, be protected from fierce winds and flares, and vast blooms of black photosynthetic plankton and algae could support the sea life.


What part does methane play in the process of producing biogas?

When you say produced, do you mean chemically made from another substance, or you do mean released into the atmosphere, or do you mean captured and stored?
Methane, or CH4, is a biogas as it is gas biologically created by organisms. Methane is created in natural processes from which it may be immediately released into the atmosphere or on much slower time scales, such as millennia and more. Methane is also released in some artificial processes, such as the flaring on oil wells. Likewise, in petroleum processing facilities, methane can leak out in other ways than is intended. So, that is how it gets out, or is "produced" as a free gas.
However, if you are asking if CH4 is produced chemically as a product of processing OTHER gases, then the answer is only a mild "sort of". When natural gas from within the Earth is removed from the ground, it contains methane, propane and other gases that are separated into their components. However, most of the nat gas IS methane to begin with. So, saying it is "produced" is sort of true and easily misunderstood.


I would recommend to do an undergraduate in physics.

I work at a department of Meteorology.  When faculty hire a new PhD student or postdoc, they often prefer those with an undergraduate in Physics than with an undergraduate in Meteorology.  The Physics degree gives a better preparation for doing science.  It has more maths and physicists are more likely to have some programming experience than meteorologists.  For most scientific positions, such programming experience is highly valuable.  It appears the meteorologists are more likely to end up in jobs like weather forecasting or energy trading, rather than science.

Although this experience may be quite localised, a physics undergraduate degree does give you a more generic background.  It's easier to catch up on the specifics of geophysics when you have a physics background, than the other way around.


Are craters on Earth covered by vegetation?

Without water there would be no multi-billion year history of plate tectonics, no glacial action, and no fluvial erosion, so the Earth would look unrecognizably primitive. But we have an atmosphere, so all the impact crater rims would be subject to aeolian erosion whilst low points, including crater bowls, would have aeolian sedimentary infill. Volcanic activity would be much more obvious, and would also tend to obliterate craters, as it has in numerous other examples in the solar system. Earth would therefore appear as a rather muted, sediment-draped version of the moon.


The atmosphere and the dispersion of greenhouse gases

The short answer is that greenhouse gases occur at all levels in the atmosphere. However, the concentrations can vary with altitude. In the case of greenhouse gases that are always in a gaseous state like CO2, Methane and Nitrous oxide, they are evenly distributed throughout the lower atmosphere (i.e. troposphere and stratosphere below ~20km), (this question & answer explain why), with only minor variations in concentration. The only notable exception is water vapour, also a powerful greenhouse gas, water is the only one that do transition between liquid, solid and gaseous states within the atmosphere, something that have as a consequence that its distribution is not homogeneous like it is for the other gases.

The actual distribution of water vapour is highly variable, something that we all know from the daily experiences of a diversity of conditions like dry weather, fog, rain, etc. However, there is some clear patterns:

Vertically, water vapor abundance falls more or less logarithmically, as it can be seen in the following figure:

(taken from AGU WATER VAPOR in the CLIMATE SYSTEM, Special Report. December 1995)

Were it falls from about 3 grams per kilogram of dry air to about 0.003 grams per kilogram of dry air at 15,000 meters of elevation. A big contrast with the tropospheric variations in CO2 for example, that are in the order of ~3-6% across the glove, with a ~1-2% seasonal cycle.

Horizontally, across the surface of the Earth, water it is much more abundant in the tropics than the poles, a pattern mostly controlled by temperature, because the capacity of air to hold dissolved water falls exponentially with temperature (as described by the first equation in my answer to this question). The following figure of the global mean water column derived from satellite data for 2009 will gives you a good sense of the typical distribution

(taken from Retrieval of total precipitable water from GOME-1, SCIAMACHY and GOME-2)

Now, if we consider higher levels of the atmosphere (>20 km), the mixing at that scale is not strong enough to smooth out the variations in concentration that arise due to the existence of sources and sinks for each greenhouse gas.
For example, methane is produced in the surface by natural and anthropocentric sources, and the biggest sink (90%) is the oxidation by hydroxyl radicals (OH) in the stratosphere. This create a fairly large vertical gradient in methane concentration. A gradient that gets smoothed out by strong mixing in the troposphere but becomes very important in the stratosphere and mesosphere. Similar phenomena creates gradients of other greenhouse gases like N2O, Ozone, and to a lesser extent CO2. These processes are nicely explained in this paper, were the following figure gives a great summary of the changes in concentration of most gases in the atmosphere:

Here you can see that, CO2 keeps a relatively fix abundance throughout the atmosphere up to 120 km, while N2O is relatively very scarce above 60 km, and Ozone below 10 km.


Both airborne planes and the Moon affect the tides, but the effect of airborne planes is so small as to be negligible.

From your sources the mass of a Boeing 747 ($m_{747}$) is $447.696$
$(10)^3$ $kg$.
Likewise, from your sources, the mass of the Moon ($m_{Moon}$ is
$7.347$ $(10)^{22}$ $kg$.
Typically a 747 would fly at an altitude ($r_{747}$) of around $30$
$000$ $ft$. This is close to $10$ $000$ $m$ ($10^4$ $m$).
The distance the Moon is from the Earth ($r_{Moon}$) is $384$
$400$  $km$, which is $384.4$ $(10)^6$ $m$.

Now, Newton's Law of Universal Gravitation states, $F$ $=$ ${G.m_1.m_2}/{r^2}$

Where:
$G$ is the gravitational constant, being $6.6743$ $10^{-11}$ $m^3.kg^{-1}.s^{-2}$,
$m_1$ and $m_2$ are the masses of the two objects being considered & $r$ is the distance between them.

Because tides are being considered only the mass of water is to be considered, not the mass of the Earth. To simplify things I am assuming the area of water affect by each is the same and hence the mass of water will be the same in each case.

For the Earth and Moon system, the force of gravity will be:

$F_{E-M}$ $=$ $6.6743(10)^{-11}$ $.$ $7.347(10)^{22}$ $.$ $m_{ocean}$ $/$ $[{384.4(10)^6}]^2$ $=$ $3.3186(10)^{-5}$ $.$ $m_{ocean}$

For the Earth Boeing 747 system, the force of gravity will be:

$F_{E-747}$ $=$ $6.6743(10)^{-11}$ $.$ $447.696(10)^{3}$ $.$ $m_{ocean}$ $/$ $[{(10)^4}]^2$ $=$ $2.9881(10)^{-13}$ $.$ $m_{ocean}$

Dividing $F_{E-M}$ by $F_{E-747}$ the gravitational force of the Moon is $111$ $060$ greater than that of the plane.

If the tides produced by the Moon are up to $10$ $m$, then the maximum height of a tide produced by a 747 would be around $0.099$ $mm$.


Why does volcanic dust pose such a hazard to air travel?

Particle size is the key issue. Saharan loess (wind-blown dust) must have a small enough particle size that it can be lofted by ordinary wind speeds: typically, it is in the 20-50μm size range.

Particle sizes lofted into the upper atmosphere during explosive volcanic eruptions can be much higher: "The explosive ash was bimodal in size distribution with peaks at about 25- and 200-μm diameter... For the
typical ash, diameter peaked at approximately 500μm" (Gislason et al., 2011), though this effect only has particular significance in close proximity to the vent.

The risk to aircraft is explained:

  Fears about danger to aircraft arose from an incident when a British Airways 747 flew through an ash cloud during the 1982 eruption of Mount Galunggung in Indonesia. The pilot reported sparks from the windows and wings as ash sandblasted all surfaces and all four jet engines failed when melted ash coated their interior.

(There's an absolutely classic paper on this, and a lot of the literature is well worth a read for the sheer understated "well, yep, that was a problem.")

In fact the ash lofted across Europe following the Eyjafjallajökull eruption was mostly below 63μm in diameter, since that's what can persist without rapidly sedimenting out, but the explosive nature of the initial eruption meant that "... even the nanoparticles are far from round. Their sharpness makes them particularly abrasive." In contrast, loess has been extensively weathered. The authors add: "The very sharp, hard particles put aircraft at risk from abrasion on windows and body and from melting in jet engines."

For more details on volcanic ash and turbine engines, see Gunn & Wade and, for that matter the rest of the volume.


How can we distinguish fold and cycle of sedimentation on a remote sensing image or in the field?

You need to take a look at lithology changes and stratification.
On a fold the stratification is parallel to the fold, while on a transgressive-regressive cycle it crosses the v form.

Source: Own work with Inkscape.
At the field the best is to look up to lithology changes and define how is stratification spatially related with the main shape.
You can easily distinguish stratification on a 2D log. From a remote sensing image it would be distinguishable if you have an outcrop that crosses the shape.


Which percentage of $\text{CO}_2$ emissions are human made emissions?

First of all, the amount of carbon cycling trough the Earth's system is irrelevant to the discussion of the changes in atmospheric $\text{CO}_2$ concentration or ocean acidification. In the same way that the volume of water cycled by the filtering system of a swimming pool is irrelevant to the level of the pool. What matters are the net inputs and outputs of water.

Let's look at this diagram of the Earth's carbon storage and fluxes through the carbon cycle.

Figure by Dave Bice at Carleton College.

The total amount of carbon is indeed huge, and the total fluxes add up to almost 700 Gigatons of carbon per year. Note that only ~400 Gt are transferred as $\text{CO}_2$, the rest is organic matter.

The number in the diagram are not precise, but they are very good approximations. The figure given in the diagram for humans burning fossil fules is 6 Gt of carbon, that corresponds to 22 Gt of $\text{CO}_2$, which added to other human made emissions probably add up to something similar to the 29 Gt of the reference you cited.

The amount of $\text{CO}_2$ released by volcanic activity varies widely in time, but the amount given in the figure is an average value, and amounts to 0.6 Gt of Carbon, equivalent to 2.2 Gt of $\text{CO}_2$. But pretty much the same amount is removed by subduction. Therefore, volcanic activity is not a significant LONG TERM source of $\text{CO}_2$. And by long term I mean millions of years.

So you can argue that natural emissions are larger than human emissions. Sure. The respiration of plants and animals produce 8 times more $\text{CO}_2$ than humans, but plants take it back through photosynthesis.

Atmospheric $\text{CO}_2$ have varied widely through Earth's history, but in the last several thousands years it have been pretty stable, because all the sources were in balance with the sinks, leading to a very small net change in $\text{CO}_2$ concentration in the atmosphere and oceans (there in the form of carbonic acid).

However, this balance was disrupted by the industrial revolution and human emissions, mostly due to the use of fossil fuels.

Going back to the swimming pool analogy: evaporation might be tiny compared with the volume of water turned around by the filtering system, but give it long enough time and your swimming pool will be dry.

We added a source of carbon in the carbon cycle, and if we don't remove it or add an equivalent sink (carbon sequestration), the concentration of $\text{CO}_2$ in the atmosphere and carbonic acid in the oceans will keep rising.

Returning to your question, using the figures in the diagram, human emissions would account for ~3% of total emissions. But that doesn't matter at all. The point is that human emissions are the ones upsetting a system that was in balance, and are triggering an increase in atmospheric $\text{CO}_2$ concentrations and consequent ocean acidification.


What is the chasm in the Arctic on Google satellite map?

You probably realise this, but you're not seeing that directly from satellite photos. Google Earth (or the "satellite" view in Google Maps) shows direct imagery on land, but underwater it shows a hillshaded view of bathymetry. So you're looking at the shape of the seabed.

With that said, I think this is the nothernmost part of the Mid-Atlantic Ridge, possibly the part known as the "Mohns Ridge". You'll see a similar line, coming and going, all the way from here down to the middle of the South Atlantic. There's a deep valley with mountains on either side. It's the boundary between two tectonic plates, where new seabed is slowly created as the Atlantic widens.

No, you should not be worried about it :-)


You're asking

  Why do human populations concentrate near fault lines, volcanoes, etc.?

But the real question is

  Do human populations concentrate near fault lines, volcanoes,
  etc.?

And the answer is not necessarily positive. Let's look at where earthquakes are:

and active volcanism:

Both maps are from Volcano Discovery. Here's a population density map:

Couldn't find the source for that, but a similar interactive website is this one: http://luminocity3d.org/WorldPopDen/

Finding a 1:1 correlation between these two natural hazards and population density is very hard. Most of the World's population reside in India, China, Europe, central Africa, and east North America. All of these areas not particularly hazardous in terms of fault lines and volcanoes. Other volcano-abundant areas are only populated if they're around the tropics (Mexico, Indonesia).

So no, the answer is that human population do not concentrate near fault lines or volcanoes more than they concentrate elsewhere.

On a local scale, however, volcanic soils are fertile and an excellent place to grow food. This might attract people to volcanoes, because food is vital for life and a maybe-yes-maybe-no threat of a volcano (particularly if it's not obviously active) is a lower priority thing for most people. Also see the interesting story of Pinatubo.

Sometimes, people did not know there was a hazard. Parícutin is a volcano in Mexico that just appeared out of nowhere in 1943. Christchurch, NZ, was considered a low earthquake risk zone until it was struck by several quakes in the recent years.

There is some truth to your two guesses that storms provide water for food and mountains lead to rivers which also provide water for food. But it's not a direct relationship. Think of the Nile river, which gets the water from mountains far south but feeds millions in Egypt. There are many more other examples.


Why is the Ozone Layer 'hole' more pronounced in the Southern Hemisphere?

Two significant factors that influence the size of the ozone hole over the southern pole are temperature and the polar vortex.

A number of sources confirm that the ozone hole increases in size when the temperature over Antarctica is colder. (Parrondo et al, The Ozone Hole, Sam Houston State University),

The polar vortices that form over the northern and southern poles are different because the northern vortex forms over water that is surrounded by land, whereas in the southern hemisphere the situation the opposite; the vortex forms over land surrounded by water. Because of this, Antarctica "is meteorologically isolated from air at higher latitudes during winter".

  This physical condition forms an isolated air mass swirling over Antarctica called the south polar vortex. In the air of the polar vortex, the temperatures drop to very low levels in the stratosphere, below -80 degrees Celsius. At these temperatures, chemicals present in the stratosphere freeze out and form polar stratospheric clouds (PSCs). It is the chemical reactions that occur on the PSCs that result in the large decrease in ozone during each austral spring over Antarctica that we called the Antarctic ozone hole.

Chlorine and fluorine oxides, produced by stratospheric photolysis (sunlight induced decomposition) of Chlorofluorocarbons (CFCs) also contribute to the depletion of ozone. During the southern winter, Antarctica is predominately dark due to the lack of sunshine. With no sun light photolysis of CFCs does not occur. During the southern summer when Antarctica is continuously sunlit CFCs decompose, further reducing ozone levels within the polar vortex.


There are craters on the Earth, Arizona's Meteor Crater being perhaps the best-known example.  The reason that there aren't a lot more (obvious) ones is that the Earth has lots of dynamic processes, ranging from weather to plate tectonics, that gradually erase them.  The Moon doesn't have these things, so craters last for billions of years.