摘要:
海潮模型作为时变重力场反演中的重要力模型之一，研究其模型误差对反演精度的影响具有重要的科学意义。Mascon（mass concentration）解是地球时变重力场表征方式之一，其关注信号的空间分布特征，提供了分析海潮模型误差影响机制的全新视角。本文基于动力学法恢复Mascon解的基本原理，建立闭环数值仿真平台，重点研究了海潮模型误差对时变重力场Mascon解的精度影响，主要研究结论如下：（1）海潮模型中未建模的潮波信号会导致显著条带误差，在海洋上以条带误差的形式存在，在陆地上则会干扰时变信号的精细建模。（2）海潮模型误差存在系统差异，在浅海区域及高纬度地区表现明显，对于南北极区域时变信号的提取影响显著，中低纬地区浅海区域的影响不可忽略。
Abstract:
Objectives: The ocean tide model (OTM), as one of the significant background models in the inversion of the temporal gravitational field, is of considerable scientific significance to investigate the impact of its model noise on the accuracy of the inversion of the temporal gravity field. The Mascon (Mass Concentration) solution is one of the representations of the Earth's temporal gravity field, which focuses on signal’s spatial pattern, providing a new perspective in spatial domain on the impact of OTM error. Methods: In this paper, with EOT11a serving as the baseline, the differences of model FES2004, EOT11ag, FES2014b and EOT20, were utilized to simulate real OTM errors. Besides, based on modified dynamic method for Mascon solution, a closed-loop numerical simulation experiment was conducted for low-low satellite-to-satellite tracking mission. By conducting simulations, the spatial distribution of OTM errors can be determined from the differences in satellite along-track perturbations calculated by various models. The impact on the Mascon solution can be assessed by comparing the results to a baseline error-free outcome. Results: The spatial distribution of acceleration residuals showed that: large magnitude of OTM errors exhibited in high latitude region for FES2014b and EOT20, as they shared identical systematic biases in such region; FES2004 model differed in shallow sea areas at mid-to-low latitude, attributed to its modeling method; additionally, while FES2014b and EOT20 contained more tidal components, there were noticeable errors in ocean area. For the Mascon results, the impact of OTM error showed different characteristics: the OTM errors had little influence on the inversion of signals within continental regions at mid-to-low latitude; the systematic OTM errors in high latitude region may cause aliasing with signals in such area; the unmodeled tidal signals caused significant north-south striping errors in ocean area. Conclusions: The main research conclusions are as follows: (1) High-frequency tidal signals within ocean tide models lead to significant striping errors. These manifest as striping errors over the oceans and interfere with the fine modeling of signals on land. (2) Systematic differences exist in ocean tide model errors, notably evident in shallow sea areas and high-latitude regions. These errors significantly affect the extraction of time-varying signals in polar regions and cannot be ignored in shallow sea areas at mid-to-low latitudes.
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