Abstract:
Objectives As a primary parameter of glacier movement, glacier velocity is widely applied in research fields such as glacier mass balance and dynamics, climate change, and hydro-climate models throughout the cryosphere. Meteorological factors play an essential role in the glacier movement by changing the glacier mass balance and hydraulic characteristics. Therefore, the glacier velocity may have the same seasonal characteristic as meteorological factors.
Methods DEM(digital elevation model)-assisted offset tracking method was applied to extract the surface velocity of Yalong glacier with 31 Sentinel-1 radar images from November 2017 to November 2020. Combined with the area change of the glacial tongue and meteorological factors (e.g., average temperature, precipitation, snowfall days and average sunshine hours), the seasonal velocity change of Yalong glacier was analyzed.
Results The velocity distribution of Yalong glacier shows that there is high velocity in the upper part and low velocity in the lower part, and the velocity in the mainstream is obviously higher than that on both sides. Thiry sets of data prove that the variation of glacier velocity has apparent seasonality, with high velocity characteristics in summer and low in winter and spring. The variation of the glacial tongue has seasonal characteristics consistent with the glacier velocity, the glacial tongue area in winter is significantly larger than in summer. One possible reason is that glaciers have a higher velocity in summer, and most of the ice enters nearby glacial lakes as the glaciers melt or move.
Conclusions The analysis of meteorological factors such as temperature, precipitation, and sunshine proves their promoting effect on glacier movement. Meanwhile, the temperature effect relatively lags in winter and spring and there is no timely feedback. In terms of the influence of meteorological factors, the temperature has the most apparent effect on glacier movement, followed by rainfall, and sunshine has a minor effect.
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