Spatio-Temporal Change of Snow Cover and Its Response to Climate over the Tibetan Plateau Based on an Improved Daily Cloud-Free Snow Cover Product

Wei Wang,Tiangang Liang,Hongjie Xie,Xiaodong Huang,Jie Deng

doi:10.3390/rs7010169

Abstract

Using new, daily cloud-free snow-cover products, this study examines snow cover dynamics and their response to climate change. The results demonstrate that the daily cloud-free snow-cover products not only posses the advantages of the AMSR-E (unaffected by weather conditions) and MODIS (relatively higher resolution) products, but are also characterized by high snow and overall classification accuracies (~85% and ~98%, respectively), substantially greater than those of the existing daily snow-cover products for all sky conditions and very similar to, or even slightly greater than, those of the daily MODIS products for clear-sky conditions. Using the snow-cover products, we analyzed the snow cover dynamics over the Tibetan Plateau and determined that the maximum number of snow-covered days (SCD) in a year followed a decreasing tendency from 2003 to 2010, with a decrease in snow-covered area (SCA) equivalent to 55.3% of the total Tibetan Plateau area. There is also a slightly increasing tendency in the maximum snow cover area (SCA), and a slightly decreasing tendency in the persistent snow cover area (i.e., pixels of SCD > 350 days) was observed for the 8-year period, which was characterized by increases in temperature (0.09 °C/year) and in precipitation (0.26 mm/year). This suggests that, on the Tibetan Plateau, changes in temperature and precipitation exert a considerable influence on the regional SCD and SCA, as well as the distribution of persistent snow cover.

Highlights

Snow cover, as an important component of land cover, is one of the most active natural materials on the Earth’s surface
A series of algorithms have been developed for the elimination of cloud obscuration from MODIS and AMSR-E snow-cover products, such as the daily Terra-Aqua image combination [13,16], temporal deduction [14,17,18], the snow-line method (SNOWL) [19] and multi-sensor combinations [15,20,21]
The results demonstrate that the snow-cover dynamics on the Tibetan Plateau (TP) influence the atmospheric circulation and the weather system in East Asia, which further influence the climate of China [34,41,42]

Summary

Introduction

As an important component of land cover, is one of the most active natural materials on the Earth’s surface. A series of algorithms have been developed for the elimination of cloud obscuration from MODIS and AMSR-E snow-cover products, such as the daily Terra-Aqua image combination [13,16], temporal deduction [14,17,18], the snow-line method (SNOWL) [19] and multi-sensor combinations [15,20,21]. These methods effectively reduce the high-cloud obscuration in the daily MODIS snow-cover products for the monitoring of SCA dynamics. A composite of optical and passive-microwave snow-cover products can completely eliminate the contamination by clouds, though with a reduced accuracy compared to those of optical snow-cover products under conditions of clear skies because of the low spatial resolution of the AMSR-E snow data [15]

Methods

Results

Conclusion