Improved De-Aliasing for Gravity Field Modelling with GRACE

所提出的工作解决了GRACE数据分析中的主要遗留问题之一，即大气和海洋去混叠。从目前的角度来看，这是GRACE重力场性能和所有后续研究的限制因素。去混叠是消除GRACE轨道及其观测采样不足造成的明显质量变化的过程。可以通过两种方式改进去混叠。(1)解混叠所需的大气和海洋压力场不得视为无误差。为此，应通过与其他模型数据或独立观察结果进行比较，对关键参数进行广泛分析。这项工作的结果应是所需参数的代表性误差测量。(2)应更好地理解完整的采样和混叠模型，并应开发和实施从代表性误差到重力场的误差传播。对于取样和混叠模型，应考虑到所有已知的质量效应以及轨道特征和现有观测结果。在最后一步中，所有结果都应考虑到重新计算均匀GRACE重力场时间序列，并将其用作优先方案内后续研究的投入。

The work proposed addresses one of the main remaining problems in the GRACE data analysis, which is the atmospheric and oceanic de-aliasing. From the current perspective this is the limiting factor for the GRACE gravity field performance and for all follow-on studies. The de-aliasing is the process to remove apparent mass variations caused by the under-sampling of the GRACE orbit and its observations. The de-aliasing can be improved in two ways. (1) The atmospheric and oceanic pressure fields required for the de-aliasing shall not be regarded as error free. For this purpose extensive analysis of the key parameters by comparison with other model data or with independent observations shall be done. Outcome of this work shall be representative error measures for the required parameters. (2) The complete sampling and aliasing model shall be better understood and the error propagation from the representative errors to the gravity field shall be developed and implemented. For the sampling and aliasing model all known mass effects as well as the orbit characteristics and available observations shall be taken into account. In a final step all results shall be taken into account for a re-computation of a homogeneous GRACE gravity field time series, which shall be used as input for subsequent studies within the priority programme.