SWOT宽刈幅干涉测高卫星数值模拟:以南海海平面变化监测为例

Numerical Simulation of Sea Level Variations from SWOT Swath Altimetry Satellite:A Case Study in the South China Sea

以中国南海及周边区域为例,利用ECCO2海洋模式数据模拟的SWOT观测数据评估SWOT的海平面长期观测能力。分析SWOT模拟误差表明,相位误差和横滚误差占主导,并且距离星下点越远误差越大。通过空间平滑对模拟的误差进行消除,南海地区SWOT的观测与海洋模式真值的均方根误差从4 cm降低到2 cm。对SWOT的观测和海洋模式信号进行分析发现,SWOT观测误差的空间分布基本呈南北条带状,这主要受卫星宽刈幅沿轨观测方式的影响,与海平面变化信号强度无关。进一步提取SWOT一条轨迹进行滤波和10 km×10 km网格插值,结果表明,2 km空间分辨率的地转流估计结果受噪声影响较大,而10 km分辨率结果更接近真值。

This paper analyzes the capability of SWOT to monitor SLV in South China Sea using numerical simulation observations and ECCO2 model data.Based on the SWOT simulator,we comprehensively analyze the simulation errors of SWOT,in which phase error and roll error are dominant errors;generally the farther away from the nadir points,the larger the error.The root mean square error between SWOT and the truth value can be reduced from 4 cm to 2 cm after eliminating the error by spatial smoothing,which improves the reliability of the results.Further analysis indicates that the spatial pattern of SWOT error is mainly affected by the along-track observation mode and is independent of the original SLV signal amplitude.Then,we further analyze one track of SWOT with grid cell sizes of 10 km,respectively.The geostrophic current results show that the simulated results with a resolution of 10 km agree with the output of the ocean model better,while the result with 2 km interpolation is significantly affected by noise.