Glacier changes and surges over Xinqingfeng and Malan Ice Caps in the inner Tibetan Plateau since 1970 derived from Remote Sensing Data

Abstract. The inner Tibetan Plateau region is a glacierised area with heterogeneous variations. However, the detailed glacier area and mass changes in this region prior to the year 2000 are scarce, and there are limited processes available to understand this heterogeneity. In this paper, we present an integrated view of the glacier area and its mass changes for Mt. Xinqingfeng and Mt. Malan of the inner Tibetan Plateau as derived from topographic maps, Landsat, ASTER, SRTM DEM, and TerraSAR-X/TanDEM-X for the period of 1970–2012 and 1970–2018, respectively. Our results show that the glaciers experienced weak shrinkage in area by 0.09 ± 0.03 % from 1970 to 2018, but there was a median mass loss at a rate of 0.22 ± 0.17 m w.e. a⁻¹ and 0.29 ± 0.17 m w.e. a⁻¹ during 1999–2012 in Mt. Xinqingfeng and Mt. Malan respectively. The glaciers of Mt. Malan have had a lower total mass loss of 0.19 ± 0.14 m w.e. a⁻¹ during 1970–1999. The mean velocity of the glaciers during 2013–2018 was 0.16 m d⁻¹, as demonstrated from the Global Land Ice Velocity Extraction from Landsat 8 (GoLIVE). The Monuomaha Glacier and Zu Glacier together with another 5 glaciers displayed the surging or advancing characteristics during the observation period. These glaciers showed have a long active period of time and comparatively low velocities, which suggests that thermal controls are important for the surge initiation and recession. The ablation area or accumulation area exhibited small slopes with velocities that were too slow to remain in balance with the accumulation rate; thus, they required surging to transport mass from the reservoir area down the glacier tongue.