Refined estimation of lake water level and storage changes on the Tibetan Plateau from ICESat/ICESat-2

Lakes on the Tibetan Plateau (TP) are sensitive indicators of climate change due to minimal disturbance by human activities. Estimations of lake water levels and storage variations on the TP are essential in evaluating water resources and modeling hydrologic processes in high-altitude endorheic basins. By integrating the ICESat/ICESat-2, Global Surface Water dataset, and HydroLAKES dataset, this study puts forward plateau-scale research of lake level changes and further estimates water storage changes on the TP during 2003-2019. The number of lakes observed by ICESat-2 is nearly three times as large as that by ICESat. There are 242 lakes over 1 km(2) that can be observed by combining both ICESat and ICESat-2. These lakes with available data present a mean water-level change rate of 0.20 +/- 0.04 m/yr in 2003-2019. A total water storage change of 11.51 +/- 2.26 Gt/yr for all lakes on the TP is estimated by combining the two-generation spaceborne laser altimetry missions. Besides, water-level change rates of the inner TP lakes during the ICESat era (2003-2009) and joint mission period (2003-2019) are compared to analyze the spatio-temporal variation characteristics of these lakes. The lakes of the inner TP show average rates of water-level change in two periods are 0.20 +/- 0.05 m/yr and 0.26 +/- 0.03 m/yr, respectively. The examination of water vapor transport over the inner TP indicates that the accelerated water-level rises in the northern TP, yet deceleration in the southern part may be tightly related to the stronger water vapor transport in the north.