Abstract
As the largest valley glacier in the Qilian Mountains, the Laohugou glacier No. 12 (LHG12) has shrunk significantly since 1957. In this study, two topographic maps and a WorldView-2 satellite stereopair image data were used to assess the volume and cumulative mass balance of LHG12 located at the western Qilian Mountains during 1957–2015. During the study period, the LHG12 exhibited changes in two processes: slightly ablation and stability in a brief period during 1957–1989 and strong melting and accelerated ablation during 1989–2015. During 1957–2015, the volume of LHG12 decreased by 0.38 km3, the average thickness decreased by 17.23 m, the cumulative mass balance (MB) was −14.69 ± 3.00 m w. e., and ablation was found glacier-wide. By comparing the previous MB simulation and digital elevation model (DEM) differencing results, it was found that the MB simulation results underestimated the strong melting trend of LHG12 since the 1990s. Temperature rose, especially in autumn and winter, and could cause the ice temperature of LHG12 to increase, and LHG12 may become more sensitive to climate change.
Highlights
Due to global warming, glaciers have shrunk significantly worldwide, and much of this loss was not reversed (Moon, 2017; Liu et al, 2020; Shean et al, 2020)
The aims of this study are (1) to generate authentic data for mass balance simulations; (2) to generate the glacier surface elevation changes using two topographic maps and a WorldView2 image and to calculate the glacier volume change; and (3) to obtain the glacier wide net mass loss based on the mass balance conversion using the digital elevation model (DEM) differencing algorithm
850 ± 60kg · m−3 was used, which is recommended for periods of longer than 5 years, with stable mass balance gradients, the presence of a firn area, and volume changes that significantly differ from zero (Huss, 2013)
Summary
Glaciers have shrunk significantly worldwide, and much of this loss was not reversed (Moon, 2017; Liu et al, 2020; Shean et al, 2020). Glacier mass balance (MB), which is a key component in glaciology, is an important factor for studying the changes in the climate, water resource, and sea level (Zemp et al, 2015; Sold et al, 2016). Glacier mass balances have been considered to be sensitive indicators of climate change (Oerlemans and Fortuin, 1992). Combining traditional observations with satellite altimetry and gravimetry, glacier mass budgets were reconciled in order to obtain an estimate of the glacier contribution to sea level change in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, but the analysis was only possible over a short time period (Gardner, 2013). Glacier mass balance can be monitored using traditional glaciological or geodetic methods.
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