基于SWOT卫星模拟数据的青藏高原湖泊水位与面积测量精度评估

Accuracy assessment of lake level and area measurement in the Qinghai-Tibet Plateau using simulated SWOT satellite data

青藏高原作为“亚洲水塔”,密集分布着众多高山湖泊,其湖泊数量与面积约占我国湖泊的一半。青藏高原湖泊作为气候与环境的“指示剂”,在时间序列上监测这些湖泊的水位与水量变化至关重要。2022年12月发射的地表水与海洋地形(SWOT)卫星将以前所未有的高时间分辨率和面状测高模式监测近乎全球的地表水动态。在数据正式向科学界公开前,有必要对SWOT卫星的性能及测量精度进行评估。本文使用SWOT卫星模拟观测生成器,实现了青藏高原部分湖泊水位与面积的模拟观测,并结合水位计数据,对SWOT卫星在时间失真、测高误差和面积误差方面的测量精度评估。结果表明,不同数据采集间隔的时间失真平均百分比误差小于4.1%,测高误差平均小于3 cm,面积误差小于湖泊面积的7%。该研究的开展为SWOT卫星在青藏高原湖泊上的应用奠定了基础,将更好地理解未来湖泊变化对气候变化的响应。

As the“water tower of Asia”,the Qinghai-Tibet Plateau is densely covered with alpine lakes,accounting for about half of China s lakes in both number and area.These lakes serve as critical indicators of climate and environmental conditions,highlighting the significance of monitoring their temporal variations in water level and volume.Launched in December 2022,the Surface Water and Ocean Topography(SWOT)mission will revolutionize our ability to observe global surface water dynamics,providing unprecedented temporal resolution and areal altimetry patterns.However,prior to the official release of SWOT satellite data to the scientific community,it is important to assess its performance and measurement accuracy.To achieve this goal,this study uses the SWOT simulator to facilitate simulated observations of water levels and areas of selected lakes on the Qinghai-Tibet Plateau.These simulated results are then combined with in-situ data to assess the SWOT satellite s measurement accuracy in terms of temporal aliasing,altimetry errors,and area errors.The results show that the mean average percentage error of the temporal aliasing of the subsampled data is less than 4.1%,the average height measurement error is less than 3 cm,and the area error is less than 7%among these lakes.The development of this study has laid the foundation for the application of SWOT satellites on the lakes of the Qinghai-Tibet Plateau to better understand the response of future lake changes to climate change.