Data, methods and perspectives of optical stereo and bistatic SAR satellites for monitoring glacier thickness change in high-mountain Asia
Glacier thickness change is the most important indicator to assess the regional ice storage change, and glacier eleva-tion measurements mainly based on optical stereo satellites and bistatic interferometric SAR satellites has become the primary means to assess the change of ice storage on a large scale. Firstly, this paper summarizes the main optical and radar satellite data and their measurement accuracy currently applied to glacierized areas in the high-mountain Asia. Then, we compile and summarize the methods of satellite monitoring of glacier thickness change (i.e. supervised-corrected DEM differencing meth-od, automated-corrected DEM differencing method, time-series DEM parameterized regression method and time-series DEM non-parameterized regression method) and their applications. It is found that the current research suffers from some problems such as inaccurate elevation estimation in snow-covered glacier zones, inaccurate radar penetration depth estimation, and diffi-culty in monitoring seasonal glacier thickness variation, which leads to extremely limited understanding of some important local processes of glacier changes. Finally, this paper discusses potential research directions concerning the monitoring of glacier thickness changes, and suggests that both the use of archived satellite data and the future high spatial-temporal resolution ob-servation programs and the fusion of multi-source altimetry data will help solve the problems currently faced.