Research on Glacier Elevation Variability in the Qilian Mountains of the Qinghai-Tibet Plateau Based on Topographic Correction by Pyramid Registration

As the ‘Third Pole’ of the world, the Qinghai-Tibet Plateau is also known as the Asian Water Tower. The glaciers covering its surface can reflect changes in the global climate and ecological environment. Therefore, the critical need for accurate information regarding the elevation changes of the glaciers on the Qinghai-Tibet Plateau is self-evident. Here we present a method for monitoring the elevation change of the glaciers on the Qinghai-Tibet Plateau that is based on pyramid registration and terrain correction techniques. The registration results show that the average elevation difference in the stable area has been improved to a considerable extent, at least 70%. The elevation difference after registration obeys a Gaussian distribution with a mean of 0. In this study, glaciers in the Qilian Mountains of the Qinghai-Tibet Plateau were used as the experimental objects, and the changes in glacier elevation in the region were monitored over the past three years. The results show that from 2019 to 2021, the glaciers in the western Qilian Mountains thinned significantly, and the glacier elevation change rate was –0.99 ± 0.34 m/year. The changes in glaciers in the southwest and north were relatively minor, with change rates of 0.09 ± 0.94 m/year and –0.08 ± 0.79 m/year, respectively. The change rates of the two glaciers in the middle were 0.74 ± 0.84 m/year and –0.16 ± 0.85 m/year, and the glacier change rate in the northeast was –0.27 ± 0.77 m/year. Finally, combined with meteorological data analysis, it is concluded that the change in glacier elevation is primarily affected by temperature and precipitation. Among these, precipitation accounts for the dominant factor impacting glacier elevation change.