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GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L22504, doi:10.1029/2007GL031474, 2007

Recent Northern Hemisphere snow cover extent trends and implications for the snow-albedo feedback

Stephen J. Déry

Environmental Science and Engineering Program, University of Northern British Columbia, Prince George, British Columbia, Canada


Ross D. Brown

Section des Processus Climatiques, Environnement Canada à Ouranos, Montréal, Quebec, Canada


Abstract

Monotonic trend analysis of Northern Hemisphere snow cover extent (SCE) over the period 1972–2006 with the Mann-Kendall test reveals significant declines in SCE during spring over North America and Eurasia, with lesser declines during winter and some increases in fall SCE. The weekly mean trend attains −1.28, −0.78, and −0.48 × 106 km2 (35 years)−1 over the Northern Hemisphere, North America, and Eurasia, respectively. The standardized SCE time series vary and trend coherently over Eurasia and North America, with evidence of a poleward amplification of decreasing SCE trends during spring. Multiple linear regression analyses reveal a significant dependence of the retreat of the spring continental SCE on latitude and elevation. The poleward amplification is consistent with an enhanced snow-albedo feedback over northern latitudes that acts to reinforce an initial anomaly in the cryospheric system.

Received 25 July 2007; accepted 15 October 2007; published 27 November 2007.

Keywords: snow; trends; snow-albedo feedback.

Index Terms: 0736 Cryosphere: Snow (1827, 1863); 0772 Cryosphere: Distribution; 1621 Global Change: Cryospheric change (0776); 3349 Atmospheric Processes: Polar meteorology; 1632 Global Change: Land cover change.

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Citation: Déry, S. J., and R. D. Brown (2007), Recent Northern Hemisphere snow cover extent trends and implications for the snow-albedo feedback, Geophys. Res. Lett., 34, L22504, doi:10.1029/2007GL031474.