Treatment of ocean tide aliasing in the context of a next generation gravity field mission
Treatment of ocean tide aliasing in the context of a next generation gravity field mission
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DOI：
10.1093/gji/ggy145
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发表时间：
2018-07-01
影响因子：
2.8
通讯作者：
Pail, Roland
中科院分区：
文献类型：
--
作者：
Hauk, Markus;Pail, Roland
重力恢复和气候实验（GRACE）的时间重力场解由于待恢复信号的欠采样而遭受时间混叠误差。G.水文学）、去混叠模型（通常是大气和海洋）的不确定性以及不完善的海潮模型。特别是后者将是确定高分辨率的时间重力场从未来的重力任务，如GRACE后续和下一代重力任务（NGGM）的最限制因素之一。本文分析和评价了一种在几年时间跨度内对八个主要分潮的海潮参数进行联合参数化的方法。采用时变地球物理背景模型和新一代仪器技术的噪声假设，对单极对和双极对Bender型编队的低-低卫星对卫星跟踪任务进行了闭环数值模拟。与单对使命相比，结果表明，由于双对星座增强了空间和时间采样以及误差各向同性，专用潮汐成分的潮汐模型误差减少了70%。将观测周期从1年延长到3年，可使某些组成部分的潮汐误差进一步减少60%，在估计过程中考虑非潮汐质量变化可使潮汐误差减少20%到80%。作为两步方法的一部分，在第二次迭代中，在重力场反演过程中使用估计的潮汐模型进行去混叠，导致超过50%的减少海洋潮汐混淆错误的NGGM本德型形成。
Current temporal gravity field solutions from Gravity Recovery and Climate Experiment (GRACE) suffer from temporal aliasing errors due to undersampling of signal to be recovered (e. g. hydrology), uncertainties in the de-aliasing models (usually atmosphere and ocean) and imperfect ocean tide models. Especially the latter will be one of the most limiting factors in determining high-resolution temporal gravity fields from future gravity missions such as GRACE Follow-On and Next-Generation Gravity Missions (NGGM). In this paper a method to co-parametrize ocean tide parameters of the eight main tidal constituents over time spans of several years is analysed and assessed. Numerical closed-loop simulations of low-low satellite-to-satellite-tracking missions for a single polar pair and a double pair Bender-type formation are performed, using time variable geophysical background models and noise assumptions for new generation instrument technology. Compared to the single pair mission, results show a reduction of tide model errors up to 70 per cent for dedicated tidal constituents due to an enhanced spatial and temporal sampling and error isotropy for the double pair constellation. Extending the observation period from 1 to 3 yr leads to a further reduction of tidal errors up to 60 per cent for certain constituents, and considering non-tidal mass changes during the estimation process leads to reductions of tidal errors between 20 and 80 per cent. As part of a two-step approach, the estimated tide model is used for de-aliasing during gravity field retrieval in a second iteration, resulting in more than 50 per cent reduction of ocean tide aliasing errors for a NGGM Bender-type formation.