Precise topography assessment of Lop Nur Lake Basin using GLAS altimeter

Lop Nur is a dried-up salt lake lying in the eastern part of Tarim basin, which used to be the second largest lagon in China. The "ear" rings in Lop Nur attract many interests and are regarded as the lake shorelines during its recession. The topography of the lake basin is important in understanding the formation of the "ear" rings. In this paper, elevation data along three transects obtained from laser altimeter were taken as the basic material of the topography in Lop Nur. Elevation data of laser altimeter show great consistency between adjacent passes. Orthometric height (OH) derived from altimetry data and the geoid model are used to analyze the elevation characteristic along "ear" rings. The result shows the "ear" rings are basically identical in elevation, supporting the statement that "ear" rings are former lake shorelines. A discrepancy of approximately 1 meter in OH is observed on the same "ear" ring, lower in the north and higher in the south, which is found for the first time. Possible explanations could be deformation of ground surface due to earthquake or tectonic movement after the "ear" rings are formed, or tilt of water surface due to wind stress or lake current during the formation of the rings.