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

K A Luus,Y Gel,J C Lin,R E J Kelly,C R Duguay

doi:10.5194/bg-10-7575-2013

K A Luus, Y Gel + Show 3 more

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https://doi.org/10.5194/bg-10-7575-2013

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Abstract

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.

Highlights

Interactions between cryospheric, biological and atmospheric components play an important role in the Arctic climate system (Serreze and Barry, 2005), and linkages between snow water equivalent (SWE), soil moisture, air temperature and the quantity of vegetation determine the carbon balance of northern regions (Sitch et al, 2007)
Each section contains tables showing the strength of associations (R2 value) of Alternating Conditional Expectations (ACE) transformed SWE and growing-season values (Table B1), and plots indicating the optimal transformations of SWE and growing-season values according to the seven vegetation classes (Figs. 4a–c, 4d–g, 5a–c, 5d–g, 6a–c and 6d–g)
A positive, nonlinear association exists between mean annual SWE and mean growing-season air temperatures such that sites which tend to be slightly warmer tend to accumulate more snow than cooler sites

Summary

Introduction

Interactions between cryospheric, biological and atmospheric components play an important role in the Arctic climate system (Serreze and Barry, 2005), and linkages between snow water equivalent (SWE), soil moisture, air temperature and the quantity of vegetation determine the carbon balance of northern regions (Sitch et al, 2007). Northern field studies have determined that snow accumulation is influenced by the snow season climate (Sturm et al, 1995). Snow accumulation is known to be altered by vegetation species compositions. Changes in snow accumulation have been found to alter vegetation species composition at an Arctic tundra site (Wahren et al, 2005), and have been found to result in anomalous soil moisture values over the following growing season in a semiarid area of Eurasia (Shinoda, 2001). Field-scale associations between snow and growing-season land surface characteristics are relatively well understood

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