The Changing Cryosphere: Pan-Arctic Snow Trends (1979-2009)

Arctic snow presence, absence, properties, and water amount are key components of Earth's changing climate system that incur far-reaching physical and biological ramifications. Recent dataset and modeling developments permit relatively high-resolution (10-km horizontal grid; 3-11 time step) pan-Arctic snow estimates for 1979-2009. Using Micro Met and Snow Model in conjunction with land cover, topography, and 30 years of the NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA) atmospheric reanalysis data, a distributed snow-related dataset was created including air temperature, snow precipitation, snow-season timing and length, maximum snow water equivalent (SWE) depth, average snow density, snow sublimation, and rain-on-snow events. Regional variability is a dominant feature of the modeled snow-property trends. Both positive and negative regional trends are distributed throughout the pan-Arctic domain, featuring, for example, spatially distinct areas of increasing and decreasing SWE or snow season length. In spite of strong regional variability, the data clearly show a general snow decrease throughout the Arctic: maximum winter SWE has decreased, snow-cover onset is later, the snow-free date in spring is earlier, and snow-cover duration has decreased. The domain-averaged air temperature trend when snow was on the ground was 0.17 degrees C decade(-1) with minimum and maximum regional trends of -0.55 degrees and 0.78 degrees C decade(-1), respectively. The trends for total number of snow days in a year averaged -2.49 days decade(-1) with minimum and maximum regional trends of -17.21 and 7.19 days decade(-1), respectively. The average trend for peak SWE in a snow season was -0.17 cm decade(-1) with minimum and maximum regional trends of -2.50 and 5.70 cm decade(-1), respectively.