Monitoring of snowline altitude at the end of melting season in Tianshan Mountains from 1991 to 2021

Subjects: Geosciences >> Cartography submitted time 2022-12-20 Cooperative journals: 《干旱区研究》

王靖文 唐志光 邓 刚 胡国杰 桑国庆

Abstract：

The study of snowline altitude changes at the end of the melting season is helpful to predict future trends of snow systems in order to understand the regional and global climate changes. The remote sensing extraction method of region snowline altitude was developed based on the Google Earth Engine and Landsat satellite data. From 1991 to 2021, the snowline altitude at the end of the melting season in the four basins of the Tianshan Mountains was extracted. The variation characteristics of snowline altitude and its relationship with meteorological factors were carefully and accurately estimated. The results were as follows: (1) the extended snowline altitude at the end of the melting season correlated well with the snow cover extent (minimum) at end of the melting season, which was extracted by Sentinel-2. The overall accuracy was 91.6%, and the Kappa coefficient was higher than 0.9. The regional snowline altitude at the end of the melting season was accurately obtained with this model. (2) Generally, the snowline altitude at the end of the melting season in the study area showed an obvious increasing trend over the last 30 years. The increase rate was between 2.7 m·a-1 and 6.4 m·a-1 . The rise rate of the snowline altitude in the Manas River Basin was the fastest (6.4 m·a-1 ), while the rise rate of the snowline altitude in the Akeyazi River Basin was the slowest (2.7 m·a-1 ). (3) The summer temperature was the main factor that affected the change in the snowline altitude at the end of the melting season in the study area (P < 0.05), while the effect of precipitation was relatively weak.

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2000—2014年喀喇昆仑山音苏盖提冰川表面高程变化

Subjects: Geosciences >> Geography submitted time 2020-01-06 Cooperative journals: 《干旱区地理》

蒋宗立 王磊 张震 刘时银 张勇 唐志光 魏俊锋 黄丹妮 张莎莎

Abstract：喀喇昆仑山区冰川由于存在正物质平衡或跃动、前进现象，被称之为“喀喇昆仑异常”，不过该地区冰川变化差异显著，尤其是大型表碛覆盖冰川，呈现与其他类型冰川明显的差异性响应，为理解喀喇昆仑冰川异常的机理，冰川尺度的详细变化研究十分必要。音苏盖提冰川位于喀喇昆仑山乔戈里峰北坡，是中国面积最大的冰川，是典型的大型表碛覆盖冰川。通过应用TanDEM-X/TerraSAR-X（2014年2月）与SRTM-X DEM（2000年2月）的差分干涉测量方法计算音苏盖提冰川表面高程变化，并结合冰川表面流速对冰川表面高程变化和跃动进行分析和讨论。结果表明：2000—2014年音苏盖提冰川表面高程平均下降了1.68±0.94 m，即冰川整体厚度在减薄，年变化率为-0.12±0.07 m·a-1。冰川表面高程变化分布不均，其中南分支（S）冰流冰川整体减薄较为显著，冰川南分支冰流运动速度较快，前进/跃动的末端占据了冰川的主干，阻滞原主干冰川物质的向下运移（跃动），导致原主干冰舌表面高程上升；冰川厚度减薄随着海拔升高先下降后保持稳定，同时呈现一定的波动性；低海拔表碛区域消融大于裸冰区，可能存在较薄表碛，因热传导高、覆盖大量冰面湖塘和冰崖存在，加速了冰川消融；在坡度小于30 °的区域，冰川厚度减薄随着坡度的减小而加剧；坡向朝南冰川厚度略微增加（0.01 m），西南坡向冰川厚度略微减薄（-0.03 m），其他坡向冰川厚度减薄明显。近14 a来，表碛覆盖的音苏盖提冰川表面高程整体下降表明物质处于亏损状态，冰川跃动导致局部冰川表面高程的增加。

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