Elevation change of the Urumqi Glacier No.1 derived from Sentinel-1A data

Accurate measurements of glacier elevation changes play a crucial role in various glaciological studies related to glacier dynamics and mass balance. In this paper, glacier elevation changes of Urumqi Glacier No.1 between August 2015 and August 2017 were investigated using Sentinel-1 A data and DInSAR technology. Meanwhile, the atmospheric delay error was corrected with the MODIS MOD05L2 products. The weight selection iteration method was applied to calibrate the glacier elevation changes in the mass balance years 2015-2016 and 2016-2017. Finally, the geodetic method was employed to calculate the elevation change values of individual stakes of Urumqi Glacier No.1. Moreover, the elevation change values corrected by the weight selection iteration method were verified. Results showed as follows:(1) the elevation of Urumqi Glacier No.1 glacier affected by atmospheric delay was 1.270 cm from 2015 to 2016. The glacier elevation affected by atmospheric delay from 2016 to 2017 was 1.071 cm.(2) The elevation change value of Urumqi Glacier No.1 was-1.101 m from 2015 to 2016, and the elevation of Urumqi Glacier No.1 decreased by 1.299 m from 2016 to 2017. The overall thickness of Urumqi Glacier No. 1 was thinning.(3) By comparing the elevation change results of individual stakes with corresponding points corrected by the weight selection iteration method, the mean squared errors of difference were 0.343 m and 0.280 m between the two mass balance years, respectively.(4) The accuracy of elevation change in non-glaciated areas was 0.039 m from 2015 to 2016 and 0.034 m from 2016 to 2017. Therefore, it is reliable to use Sentinel-1 A data and the study method proposed in this paper to calculate the elevation change of mountain glaciers with very low horizontal movement.

近期青藏高原普若岗日冰原冰川跃动特征

The Puruogangri Ice Field(PIF), classified as an ultra-continental glacier, is considered extremely stable. However, several glaciers in this area have recently experienced surge events with significant instability and information on surge-type glaciers(STGs) in this region remains scarce. In this study, we identified six STGs and reported the observed characteristics of their surging behavior in the region by mapping glacier boundaries, surface flow velocity information, and glacier surface elevation changes using recent Landsat satellite imagery and shuttle radar topography mission(SRTM), TanDEM, and ASTER digital elevation model(AST14DEM) data. These data provide valuable insights into recent glacial processes, flow instability, and rapid glacial movement. During the active phase of the glaciers,all exhibited frontal advances and changes in surface elevation. Owing to limitations in the satellite imagery, flow velocity profiles were only available for glaciers N1(G089071E33998N),NE1(G089128E33943N), and SE3(G089278E33913N) during the active phase. However,these results effectively reflect the velocity variations in both glaciers before, during, and after the surge. Based on the characteristics of the STG, scientific expeditions, and meteorological data, we believe that the surge in PIF was largely influenced by glacier meltwater and changes in subglacial drainage systems.