基于ICESat的南极冰下湖活动监测方法

Detection of Antarctic Subglacial Lakes Activities Using ICESat Altimetry Data

南极冰下湖是冰下水文系统的重要组成部分,研究冰下湖的活动对冰下水文、冰流速、冰盖物质平衡以及海平面变化有着重要的意义。介绍了利用ICESat重复轨道算法监测冰下湖活动的方法,并针对冰下湖不同活动情况进行了仿真实验,以东南极Academy12和CookE2冰下湖为例分析了该算法在实际监测中的应用。结果表明,两个冰下湖的活动导致其冰盖表面分别产生最大约6 m的上升和最大约70 m的下降。此外,当冰下湖高程变化在ICESat数据时间段内呈恒定的变化规律时,利用全部数据和重复轨道算法可得到不受地形影响的高程变化;当高程变化规律在该时间段不恒定时,需根据实际高程变化情况选取部分测高数据解算地形,从而保证得到正确的高程变化监测结果。

Antarctic subglacial lakes form an important component of the subglacial hydrological system.The movements of some subglacial lakes have great impacts on subglacial hydrology,ice-flow velocity,mass balance of ice sheet and sea level changes.According to the deformation of the ice-sheet above the subglacial lakes,the repeat-track algorithm based on ICESat altimetry data was introduced to detect the height changes of subglacial lakes.Then simulative models were established to analyze the ice-sheet deformation caused by the different patterns of active subglacial lakes.Finally,the Academy12 and CookE2 subglacial lakes were selected to analyze the actual application of the algorithm.The results show that the ice-sheet above the Academy12 and CookE2 subglacial lakes went up 6 mand went down 70 mrespectively.All the altimetry data applied in the repeat-track algorithm is capable of detecting the right height changes when the height change patterns are steady.However,when there exists high variability of the height change patterns,the proper altimetry data should be adopted to calculate the topography in order to get the right height changes.