Pan-Arctic linkages between snow accumulation and growing-season air temperature, soil moisture and vegetation

[摘要] Arctic field studies have indicated that the air temperature, soilmoisture and vegetation at a site influence the quantity of snowaccumulated, and that snow accumulation can alter growing-season soilmoisture and vegetation. Climate change is predicted to bring aboutwarmer air temperatures, greater snow accumulation and northwardmovements of the shrub and tree lines.Understanding the responses ofnorthern environments to changes in snow and growing-season landsurface characteristics requires: (1) insights into the present-daylinkages between snow and growing-season land surface characteristics;and (2) the ability to continue to monitor these associations overtime across the vast pan-Arctic. The objective of this study wastherefore to examine the pan-Arctic (north of 60° N)linkages between two temporally distinct data products created fromAMSR-E satellite passive microwave observations: GlobSnow snow waterequivalent (SWE), and NTSG growing-season AMSR-E Land Parameters (airtemperature, soil moisture andvegetation transmissivity). Due to the complex and interconnectednature of processes determining snow and growing-season land surfacecharacteristics, these associations were analyzed using the modernnonparametric technique of alternating conditional expectations(ACE), as this approach does not impose a predefined analyticform.Findings indicate that regions with lower vegetationtransmissivity (more biomass) at the start and end of the growingseason tend to accumulate less snow at the start and end of the snowseason, possibly due to interception and sublimation. Warmer airtemperatures at the start and end of the growing season wereassociated with diminished snow accumulation at the start and end ofthe snow season. High latitude sites with warmer mean annual growing-season temperatures tended to accumulate more snow, probably due tothe greater availability of water vapor for snow season precipitationat warmer locations.Regions with drier soils preceding snow onsettended to accumulate greater quantities of snow, likely because driersoils freeze faster and more thoroughly than wettersoils. Understanding and continuing to monitor these linkages at theregional scale using the ACE approach can allow insights to be gainedinto the complex response of Arctic ecosystems to climate-drivenshifts in air temperature, vegetation, soil moisture and snowaccumulation.

[学科分类] 地球化学与岩石