Assessing Snow Phenology over the Large Part of Eurasia Using Satellite Observations from 2000 to 2016

Yanhua Sun,Wenyu Zhao,Xiaodong Huang,Tingjun Zhang,Yijing Liu

doi:10.3390/rs12122060

Abstract

Snow plays an important role in meteorological, hydrological and ecological processes, and snow phenology variation is critical for improved understanding of climate feedback on snow cover. The main purpose of the study is to explore spatial-temporal changes and variabilities of the extent, timing and duration, as well as phenology of seasonal snow cover across the large part of Eurasia from 2000 through 2016 using a Moderate Resolution Imaging Spectroradiometer (MODIS) cloud-free snow product produced in this study. The results indicate that there are no significant positive or negative interannual trends of snow cover extent (SCE) from 2000 to 2016, but there are large seasonal differences. SCE shows a significant negative trend in spring (p = 0.01) and a positive trend in winter. The stable snow cover areas accounting for 78.8% of the large part of Eurasia, are mainly located north of latitude 45° N and in the mountainous areas. In this stable area, the number of snow-covered days is significantly increasing (p < 0.05) in 6.4% of the region and decreasing in 9.1% of the region, with the decreasing areas being mainly located in high altitude mountain areas and the increasing area occurring mainly in the ephemeral snow cover areas of northeastern and southern China. In central Siberia, Pamir and the Tibetan Plateau, the snow onset date tends to be delayed while the end date is becoming earlier from 2000 to 2016. While in the relatively low altitude plain areas, such as the West Siberian Plain and the Eastern European Plain region, the snow onset date is tending to advance, the end date tends to be delayed, but the increase is not significant.

Highlights

Snow cover, an indispensable component of the cryosphere and climate system, affects the surface radiation balance through its high albedo and provides fresh water for human beings, in arid and semi-arid regions [1,2,3]
The characteristics of snow phenology are very important for studying the snow cover change response to climate change, and provide a benefit for climate models used for future forecasts [9]
Despite the high elevations and lower temperatures of the Tibetan Plateau, strong solar radiation causes the snow to melt quickly. This coupled with seriously fragmental of snow cover distribution, cause large snow classification errors on the Tibetan Plateau [41]. In those stable snow cover areas where snow-covered days are greater than 60 d, the snow agreement at most sites is greater than 80%, which indicates that these areas are the typical snow cover areas that have ideal accuracy

Summary

Introduction

An indispensable component of the cryosphere and climate system, affects the surface radiation balance through its high albedo and provides fresh water for human beings, in arid and semi-arid regions [1,2,3]. Variations of snow cover have a huge impact on ecosystems and regional climate [4,5]. Snow phenology is used to characterize snow cover changes response to climate change, and shows great seasonal and inter-annual variations. Increasing air temperature postpones the snow cover onset date in autumn and results in an earlier snow melt event in spring. The characteristics of snow phenology are very important for studying the snow cover change response to climate change, and provide a benefit for climate models used for future forecasts [9]

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Discussion

Conclusion