基于GRACE-FO的微波与激光星间测距数据的重力场模型对比分析

为分析GRACE-FO微波测距系统KBR及激光干涉测距系统LRI对时变重力场结果的影响，以动力学方法为基础，分别采用KBR数据和LRI数据反演2019-01~2021-08的90阶无约束时变重力场模型APM_KBR和APM_LRI，并进行对比分析。 从重力场模型阶方差和等效水柱高的空间分布来看，在两类测距数据完整且质量较好的前提下，两者精度处于同一水平，而当发生较多月卫星机动或其他卫星事件时会使LRI数据缺失，从而导致APM_LRI模型在该月得到的等效水柱高时间序列信噪比略低。由后验残差结果可知，APM_LRI后验残差RMS比APM_KBR减少约50%，且在高频处(大于等于60 CPR)LRI的后验残差显著低于KBR。总体来说，在现有条件下，由于背景场模型等其他因素影响，两类测距数据反演重力场的阶方差和等效水柱高结果基本一致，但后验残差上LRI测距具有更低的噪声。因此，未来可直接使用LRI测距数据探测、分析较弱的地球物理信号。

Comparative Analysis of Gravity Field Models of Microwave and Laser Ranging Data Based on GRACE-FO

In order to investigate the influence of GRACE-FO K-band ranging system and laser ranging interferometer on the time-variable gravity field model, during January 2019 to August 2021 the unconstrained 90 d/o monthly gravity field solutions APM_KBR and APM_LRI are derived by dynamic methods. In terms of degree variance from the gravity field model and the spatial distribution of equivalent water height, the accuracy of the two types of ranging data is at the same level under the condition of complete and good quality. However, satellite maneuvers or other satellite events in that month will lead to missing LRI data, resulting in a slightly lower signal-to-noise ratio of time series of the equivalent water height obtained by APM_LRI model in that month. From the perspective of post-fit residual, the RMS of APM_LRI is about 50% lower than that of APM_KBR, and the post-fit residual of LRI is significantly lower than that of KBR measurement at high frequency (≥60 CPR). In general, under the existing conditions, due to the influence of background models as well as other factors, the degree variance and the equivalent water height of gravity field from the two kinds of ranging data are basically the same, but the LRI ranging data has lower noise in the post-fit residual. In other words, LRI ranging data can be directly applied to detect and analyze tiny geophysical signals in the future.