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青藏高原湖泊水位变化是气候变化和生态环境变化研究的重要指标。随着Cryosat-2观测数据的日益丰富和处理技术的提升,可以有效监测更多湖泊的水位变化信息。本研究构建了基于噪声去除技术、改进的波形重跟踪处理算法(ImpMWaPP)和误差混合动态模型为一体的高精度湖泊水位序列提取方法,利用Cryosat-2 SARIn数据获取到133个青藏高原湖泊2010年—2018年的高精度水位序列,并分析了这些湖泊水位变化的时空变化特征。总体上,青藏高原湖泊的水位继续呈上升趋势,但上升速度较2003年—2009年趋缓,年均变化率0.159 m/a。从地域分布上,北部湖泊的水位上升最为显著,而南部湖泊的水位则趋于稳定。从时间上,2010年—2012年和2016年—2018年,大多数湖泊的水位呈现快速上涨,而其他时间水位相对稳定或略有下降。
The changes in lake level on the Tibetan Plateau are important indicators for the study of climate and ecological environment changes. In-situ gauges can measure high-precision lake level data, but they are costly to maintain and challenging to operate in remote areas. Satellite radar altimetry has now been used successfully for more than two decades to measure lake levels as an addition to gauge measurement. Monitoring the water level changes of more lakes becomes effective with the increase in Cryosat-2 observation data and the improvement in data processing technology.This study presents a high-precision extraction method of lake level time series based on noise removal, improved empirical retracker (ImpMWaPP), and error mixture model. The Cryosat-2 SARIn data were used to obtain water level time series of 133 Tibetan Plateau Lakes from 2010 to 2018, and the spatiotemporal variations of these lake levels were analyzed. The accuracy of lake level extraction was validated using in-situ measurements and Hydroweb water level products.In general, the lake levels on the Tibetan Plateau continue to rise, but the rate of increase is slower than that in the period of 2003—2009. The average annual rate of change is 0.159 m/a. From the geographical distribution, the lake levels in the northern plateau rise most significantly, while the lake levels in the southern plateau tend to be stable. The water levels of most lakes showed a rapid rise in the periods of 2010—2012 and 2016—2018, while the water levels were relatively stable or slightly decreased at other times.The results showed that the accuracy of lake level extraction in this study was higher than that of previous studies, and the change in lake levels on the Tibetan Plateau was similar to those in the previous studies. In the future work, the change in lake levels on the Tibetan Plateau will be further estimated using multi-altimeter data. We will also consider the information of lake extent and study the change in lake volume to support the exploration of climate and environmental changes on the Tibetan Plateau.