Pan-Arctic linkages between snow accumulation and growing-season air temperature, soil moisture and vegetation
Abstract. Arctic field studies have indicated that the air temperature, soil moisture and vegetation at a site influence the quantity of snow accumulated, and that snow accumulation can alter growing-season soil moisture and vegetation. Climate change is predicted to bring about warmer air temperatures, greater snow accumulation and northward movements of the shrub and tree lines. Understanding the responses of northern environments to changes in snow and growing-season land surface characteristics requires: (1) insights into the present-day linkages between snow and growing-season land surface characteristics; and (2) the ability to continue to monitor these associations over time across the vast pan-Arctic. The objective of this study was therefore to examine the pan-Arctic (north of 60° N) linkages between two temporally distinct data products created from AMSR-E satellite passive microwave observations: GlobSnow snow water equivalent (SWE), and NTSG growing-season AMSR-E Land Parameters (air temperature, soil moisture and vegetation transmissivity). Due to the complex and interconnected nature of processes determining snow and growing-season land surface characteristics, these associations were analyzed using the modern nonparametric technique of alternating conditional expectations (ACE), as this approach does not impose a predefined analytic form. Findings indicate that regions with lower vegetation transmissivity (more biomass) at the start and end of the growing season tend to accumulate less snow at the start and end of the snow season, possibly due to interception and sublimation. Warmer air temperatures at the start and end of the growing season were associated with diminished snow accumulation at the start and end of the snow season. High latitude sites with warmer mean annual growing-season temperatures tended to accumulate more snow, probably due to the greater availability of water vapor for snow season precipitation at warmer locations. Regions with drier soils preceding snow onset tended to accumulate greater quantities of snow, likely because drier soils freeze faster and more thoroughly than wetter soils. Understanding and continuing to monitor these linkages at the regional scale using the ACE approach can allow insights to be gained into the complex response of Arctic ecosystems to climate-driven shifts in air temperature, vegetation, soil moisture and snow accumulation.
Pan-Arctic uhusiano kati ya mkusanyiko wa theluji na kuongezeka kwa msimu wa joto hewa, unyevu wa udongo na mimea Abstract. Uchunguzi wa uwanja wa Arctic umeonyesha kuwa joto la hewa, unyevu wa udongo na mimea katika eneo fulani huathiri kiasi cha theluji iliyojilimbikizia, na kwamba mkusanyiko wa theluji unaweza kubadilisha unyevu wa udongo na mimea ya msimu wa kukua. Mabadiliko ya hali ya hewa yanatarajiwa kuleta joto la hewa, mkusanyiko mkubwa wa theluji na harakati za kaskazini za mti na mti. Kuelewa majibu ya mazingira ya kaskazini kwa mabadiliko ya theluji na sifa za uso wa ardhi ya msimu wa kukua inahitaji: (1) ufahamu wa uhusiano wa leo kati ya theluji na sifa za uso wa ardhi ya msimu wa kukua; na (2) uwezo wa kuendelea kufuatilia ushirika huu kwa muda mrefu katika pan-Arctic. Kwa hivyo, lengo la utafiti huu lilikuwa kuchunguza uhusiano wa pan-Arctic (kaskazini ya 60 ° N) kati ya bidhaa mbili za data za muda tofauti zilizotengenezwa kutoka kwa uchunguzi wa microwave wa AMSR-E: sawa ya maji ya theluji ya GlobSnow na NTSG ya msimu wa kukua ya AMSR-E (joto la hewa, unyevu wa udongo na uhamishaji wa mimea). Kwa sababu ya hali ngumu na ya kuunganishwa ya michakato inayoamua theluji na sifa za uso wa ardhi ya msimu wa kukua, ushirika huu ulichambuliwa kwa kutumia mbinu ya kisasa ya matarajio ya hali ya kubadilisha (ACE), kwani mbinu hii haitoi fomu ya uchambuzi iliyowekwa mapema. Utafiti unaonyesha kwamba mikoa yenye mimea ya chini (biomass zaidi) mwanzoni na mwisho wa msimu wa kukua huwa na theluji kidogo mwanzoni na mwisho wa msimu wa theluji, labda kwa sababu ya kukamata na sublimation. Joto la hewa la joto mwanzoni na mwisho wa msimu wa kukua lilihusishwa na kupungua kwa mkusanyiko wa theluji mwanzoni na mwisho wa msimu wa theluji. Maeneo ya latitudo ya juu na joto la wastani wa joto la mwaka wa kukua huelekea kukusanya theluji zaidi, labda kwa sababu ya upatikanaji mkubwa wa mvuke wa maji kwa mvua ya msimu wa theluji katika maeneo ya joto. Mikoa yenye udongo kavu kabla ya kuanza kwa theluji ilikosa kiasi kikubwa cha theluji, labda kwa sababu udongo kavu unakuwa baridi haraka na kwa kina kuliko udongo wenye unyevunyevu. Kuelewa na kuendelea kufuatilia uhusiano huu katika kiwango cha kikanda kwa kutumia mbinu ya ACE inaweza kuruhusu ufahamu kupewa katika majibu tata ya mazingira ya Arctic kwa mabadiliko ya hali ya hewa, mimea, unyevu wa udongo na mkusanyiko wa theluji.