Simulation Of Hailuogou Glacier Change In The Southeastern Tibetan Plateau Based On Remote Sensing And Numerical Model

The glacier is a sensitive indicator of climate change,as well as an important fresh water resource,which has an important impact on local climate,ecological resources and environment.With global warming,most glaciers on the Qinghai-Tibet Plateau are shrinking and thinning,especially temperature glaciers in the southeastern Tibetan Plateau.Hailuogou Glacier flows quickly and its ablation area is mainly covered by debris.As a result,field measurement is difficult to conduct,and there are few studies on the glacier dynamics and its driving factors.Based on an energy-mass balance model and the offset tracking method,changes of mass balance and surface velocity on Hailuogou Glacier are derived during 1950-2019 and 2015-2019,respectively.And then,the influencing factors of mass balance and the feedback relationship between flow velocity and mass balance are discussed.Finally,with the reconstructed mass balance,changes of glacier length and thickness of Hailuogou Glacier were simulated when the glacier reached a stable state.The results of this study can reveal the response of temperature glaciers to climate change,and lay a foundation for the comprehensive study of the interaction between climate change,glacier mass balance and glacier dynamics.The main results are as follows.（1）The annual mass balance of Hailuogou Glacier has been continuously in deficit in the past 70 years,with an average change of-0.58 m w.e.a^-1.Especially,the annual mass loss of Hailuogou Glacier has been accelerating since 2006,reaching-1.88 m w.e.a^-1.The interannual change in glacier mass balance is mainly driven by positive air temperature rising through increasing longwave incoming radiation,decreasing surface albedo and snowfall ratio besides the influence of debris cover.Further analysis suggests that large-scale atmospheric circulation patterns in the Eurasian region provides important implications for regional-to-local climate variability,enhancing the trend of the negative mass balance of Hailuogou Glacier in the southeastern TP over the past two decades.（2）The surface movement of Hailuogou Glacier is active,and the average velocity along the central flowline is 0.35±0.07 m d^-1.The velocity is fast at the firn zone and the ice fall,but slow at the upper part of the ice fall,the arch bend and the ice tongue.The interannual variation of velocity in different parts of Hailuogou Glacier is significant.From the top of the glacier to the upper part of the icefall,it first increases and then slows down,and from the arch bend to the end of the glacier,it continues to decelerate.The seasonal characteristics of glacier surface movement are obvious,and the movement speed in winter is 4.5%-25%lower than that in other seasons.（3）From 2002 to 2019,Hailuogou Glacier shrank significantly,with an average retreat rate of-9.9 m a^-1 and ice thickness thinning rate of-0.7 m a^-1.The total length of Hailuogou Glacier will shrink 0.6 km and the average ice thickness will decrease 26.0 m in 2050.By the end of the 21st century,the length of Hailuogou Glacier will be reduced by 1.2 km and the average thickness of Hailuogou Glacier will be reduced by 34.5 km if the current mass balance is maintained.The icefall is expected to disappear by 2081.