融合多源测高数据的南极伊丽莎白公主地冰下湖的动态反演

Monitoring the dynamics of Antarctic subglacial lakes is of great significance to the study of the stability of ice sheet, the thermodynamics analysis of ice sheet and the study of global climate change. Recently, it is confirmed that there is a vast subglacial lake in the interior of Princess Elizabeth Land in East Antarctica, according to the evidence from both ice surface expressions in satellite imagery and reflection characteristics extracted from airborne radio-echo sounding (RES) data. Although the state of subglacial lake along the survey line can obtained by using RES data, the exact position and dynamics of the entire subglacial lake are unknown. Therefore, this study is based on the fact that the subglacial lake activity can induce the surface elevation change of the ice sheet. A novel fusion method by using multi-source satellite altimetry data is proposed to obtain accurate surface elevation changes of ice sheet. Then, a reliable method for boundary estimation of subglacial lake is also proposed based on the surface elevation changes. Moreover, the change of surface elevation caused by the activity of this subglacial lake is further separated. Finally, the inversion method of the volume change of this subglacial lake is explored. This study can realize the long-time dynamic monitoring of this subglacial lake. The driving forces of the activity of this subglacial lake is also discussed in this research. The results of this study can be verified or supplemented with the results of RES, and can provide a scientific basis for the research on the hydrological processes and the stability of ice sheet in Princess Elizabeth Land and even the whole Antarctica.

监测南极冰下湖的动态对于冰盖稳定性研究、冰盖热力学分析以及全球气候变化研究等方面具有十分重要的意义。近期，根据冰盖表面特征的推测以及由最新冰雷达数据的验证，证实了东南极伊丽莎白公主地区域存在一个面积巨大的冰下湖。虽然冰雷达数据能够准确获得该冰下湖在测线位置上的状态，但整个冰下湖的精确空间位置和时序变化等特性尚不明确。因此，本研究基于冰下湖活动能够引起冰盖表面高程变化的事实，利用多源时序卫星测高数据，针对该研究区域提出新的多源测高数据融合分析方法，获得精确的冰盖表面高程变化。研究基于高程变化特征的冰下湖边界的可靠确定方法，分离出由冰下湖活动引起的表面高程变化量，据此反演出该冰下湖的体积变化动态，实现对该冰下湖长时间序列的动态监测，并探讨该冰下湖活动的驱动力。该研究成果可与冰雷达数据处理结果相互验证和补充，为伊丽莎白公主地乃至全南极的冰下水文过程研究及冰盖稳定性研究提供科学依据。

本项目以南极伊丽莎白公主地区域新发现的巨大冰下湖为研究对象，结合多源卫星测高数据和航空冰雷达数据，对该湖长时间序列的变化动态及其驱动力进行了深入研究，完成了项目既定的全部研究内容，达到了预期研究目标。取得的主要成果包括：1）提出了针对多源卫星测高数据的偏差改正方法，在此基础上提出了多源测高数据的优势融合方法，计算出了研究区域的表面高程异常；2）基于南极航空冰雷达数据，提出了冰下湖的多参数表达方法，进一步研究了基于机器学习方法的冰雷达图像中冰下湖的识别方法，从而将冰雷达冰下湖探测结果与卫星测高表面异常结果相结合，提出了冰下湖边界的精准确定方法；3）引入1960年代以来研究区域表面的序列光学遥感影像，分析了该冰下湖长时间序列的动态变化，并通过对伊丽莎白公主地区域冰下水文网络的分析，探讨了该冰下湖变化的驱动力。本项目的研究成果为伊丽莎白公主地乃至全南极的冰下水文过程研究及冰盖稳定性研究提供了重要的科学依据。项目研究成果发表SCI/EI学术论文10篇，申请发明专利1项，参加国内外学术会议5人次，培养毕业研究生3名。