分类： 地球科学 >> 地理学 提交时间： 2022-10-12 合作期刊: 《干旱区科学》
摘要：
Topography plays an important role in determining the glacier changes. However, topography has often been oversimplified in the studies of the glacier changes. No systematic studies have been conducted to evaluate the relationship between the glacier changes and topographic features. The present study provided a detailed insight into the changes in the two branches (east branch and west branch) of Urumqi Glacier No. 1 in the Chinese Tianshan Mountains since 1993 and systematically discussed the effect of topography on the glacier parameters. This study analyzed comprehensive recently observed data (from 1992/1993 to 2018/2019), including mass balance, ice thickness, surface elevation, ice velocity, terminus, and area, and then determined the differences in the changes of the two branches and explored the effect of topography on the glacier changes. We also applied a topographic solar radiation model to analyze the influence of topography on the incoming shortwave radiation (SWin) across the entire glacier, focusing on the difference in the SWin between the two branches. The glacier mass balance of the east branch was more negative than that of the west branch from 1992/1993 to 2018/2019, and this was mainly attributed to the lower average altitude of the east branch. Compared with the west branch, the decrease rate of the ice velocity was lower in the east branch owing to its relatively increased slope. The narrow shape of the west branch and its southeast aspect in the earlier period resulted in a larger glacier terminus retreat of the west branch. The spatial variability of the SWin across the glacier surface became much larger as altitude increased. The SWin received by the east branch was slightly larger than that received by the west branch, and the northern aspect could receive more SWin, leading to glacier melting. In the future, the difference of the glacier changes between the two branches will continue to exist due to their topographic differences. This work is fundamental to understanding how topographic features affect the glacier changes, and provides information for building different types of relationship between the glacier area and ice volume to promote further studies on the basin-scale glacier classification.
分类： 地球科学 >> 地理学 提交时间： 2022-07-18 合作期刊: 《干旱区科学》
摘要： Topography plays an important role in determining the glacier changes. However, topography has often been oversimplified in the studies of the glacier changes. No systematic studies have been conducted to evaluate the relationship between the glacier changes and topographic features. The present study provided a detailed insight into the changes in the two branches (east branch and west branch) of Urumqi Glacier No. 1 in the Chinese Tianshan Mountains since 1993 and systematically discussed the effect of topography on the glacier parameters. This study analyzed comprehensive recently observed data (from 1992/1993 to 2018/2019), including mass balance, ice thickness, surface elevation, ice velocity, terminus, and area, and then determined the differences in the changes of the two branches and explored the effect of topography on the glacier changes. We also applied a topographic solar radiation model to analyze the influence of topography on the incoming shortwave radiation (SWin) across the entire glacier, focusing on the difference in the SWin between the two branches. The glacier mass balance of the east branch was more negative than that of the west branch from 1992/1993 to 2018/2019, and this was mainly attributed to the lower average altitude of the east branch. Compared with the west branch, the decrease rate of the ice velocity was lower in the east branch owing to its relatively increased slope. The narrow shape of the west branch and its southeast aspect in the earlier period resulted in a larger glacier terminus retreat of the west branch. The spatial variability of the SWin across the glacier surface became much larger as altitude increased. The SWin received by the east branch was slightly larger than that received by the west branch, and the northern aspect could receive more SWin, leading to glacier melting. In the future, the difference of the glacier changes between the two branches will continue to exist due to their topographic differences. This work is fundamental to understanding how topographic features affect the glacier changes, and provides information for building different types of relationship between the glacier area and ice volume to promote further studies on the basin-scale glacier classification.
分类： 地球科学 >> 地理学 提交时间： 2021-02-10 合作期刊: 《干旱区科学》
摘要： The Karakoram Mountains are well known for their widespread surge-type glaciers and slight glacier mass gains. On the one hand, glaciers are one of the sensitive indicators of climate change, their area and thickness will adjust with climate change. On the other hand, glaciers provide freshwater resources for agricultural irrigation and hydroelectric generation in the downstream areas of the Shaksgam River Basin (SRB) in western China. The shrinkage of glaciers caused by climate change can significantly affect the security and sustainable development of regional water resources. In this study, we analyzed the changes in glacier area from 2000 to 2016 in the SRB using Landsat TM (Thematic Mapper)/ETM+ (Enhanced Mapper Plus)/OLI (Operational Land Imager) images. It is shown that the SRB contained 472 glaciers, with an area of 1840.3 km2, in 2016. The glacier area decreased by 0.14%/a since 2000, and the shrinkage of glacier in the southeast, east and south directions were the most, while the northeast, north directions were the least. Debris-covered area accounted for 8.0% of the total glacier area. We estimated elevation and mass changes using the 1 arc-second SRTM (Shuttle Radar Topography Mission) DEM (Digital Elevation Model) (2000) and the resolution of 8 m HMA (High Mountain Asia) DEM (2016). An average thickness of 0.08 (±0.03) m/a, or a slight mass increase of 0.06 (±0.02) m w.e./a has been obtained since 2000. We found thinning was significantly lesser on the clean ice than the debris-covered ice. In addition, the elevation of glacier surface is spatially heterogeneous, showing that the accumulation of mass is dominant in high altitude regions, and the main mass loss is in low altitude regions, excluding the surge-type glacier. For surge-type glaciers, the mass may transfer from the reservoir to the receiving area rapidly when surges, then resulting in an advance of glacier terminus. The main surge mechanism is still unclear, it is worth noting that the surge did not increase the glacier mass in this study.
分类： 地球科学 >> 地理学 提交时间： 2017-11-07 合作期刊: 《干旱区科学》
摘要： Urumqi Glacier No. 1 is a representative glacier in the inland areas of Central Asia and is the only Chinese reference glacier in the World Glacier Monitoring Service. In this study, we explored multi-decadal variations in the flow velocity of the glacier and the influencing factors based on continuous field observations and path coefficient analysis.
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