Recent glacier changes in the Tien Shan observed by satellite gravity measurements

• Glacier mass variations in the Tien Shan are investigated from GRACE.
• Significant seasonal glacier variations are found in the Tien Shan.
• The Tien Shan glaciers mass increases prior to 2005 but then decreases.
• The effect factors on glaciers changes in the Tien Shan are discussed.

The glaciers in the Tien Shan are extensive and play an important role in water cycle in central Asia. However, it is difficult to accurately monitor glacier variations in the Tien Shan due to the lack of in situ widespread measurements. In this paper, glacier mass variations in the Tian Shan are obtained and investigated from 10 years of monthly GRACE gravity solutions (January 2003–December 2012) and the WaterGAP Global Hydrology Model (WGHM), including seasonal, secular and interannual variations . Results show that significant seasonal variations of glacier mass are found with the maximum normally in April–June and the minimum around in November–December. The trends in all four regions are positive from 2002 to 2005 and negative from 2005 to 2012, indicating that the Tien Shan glaciers are increasing prior to 2005 and significantly melting after 2005. These changes are consistent with the temperature change in the Tien Shan. In addition, in the past decade the precipitation has decreased and evapotranspiration has increased, which have joint influences on glacier mass changes in different regions of the Tien Shan.