2000—2014年喀喇昆仑山音苏盖提冰川表面高程变化

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。

Surface elevation changes of Yengisogat Glacier between 2000 and 2014

The Karakoram glaciers are attracting more and more attentions for ‘Karakoram Anomaly’ due to glacier surge or positive mass balance. To understand the mechanism of the glacier surge or positive mass balance, a huge debris-covered glacier-Yengisogat glacier was selected to be investigated in detail. Yengisogat glacier, the glacier of the largest area in China, developed on the northern slope of K2 located in the Karakoram Mountains, is a dendritic glacier covered area of 493 km2 with four main tributaries and more than ten small glacier flows. TanDEM-X/TerraSAR-X data (acquired in Feb.2014) and SRTM-X dem (acquired in Feb.2000) were employed to calculate the glacier elevation change using differential interferometry method. Similar penetration depth was assumed for the same acquired season. The glacier surface elevation change and surface velocities from published articles were integrated to discuss the mass change characteristics. The results indicated that the glacier average surface elevation was decreased by 1.68±0.94 m between 2000 and 2014,which means that the glacier has lost mass by -0.12±0.07 m·a^-1.The glacier surface elevation changes showed no uniformity. The southern main tributary was decreased drastically. This was caused by rapid surface flow velocities which transfer the glacier mass from high altitude to low altitude ablation area. The southern main tributary occupied the original glacier trunk impeded the glacier mass transfer to low elevations which made the section elevation increased. The increased surface elevation in the tongue of glacier main trunk may be explained by glacier surge. Glacier surface elevation started to decrease along with the elevation increasing and then stayed stable, yet showing volatility at the same time. Surface elevation of thin debris-covered glacier in low altitude zones was prone to decrease than that of the exposed glacier ice. Glacier surface elevation was decreased more dramatically with the decreasing of glacier surface slope in the area where slope are less than 30 degrees. Surface elevation of glaciers with southern orientation was increased slightly while that with south-west orientation was decreased slightly, and the others were decreased drastically. The debris-covered Yengisogat Glacier experienced an overall surface elevation decline which indicated it had the mass loss although it had some local surface elevation increase due to the glacier surge.