Combined Ocean Tide Analysis by GRACE and Altimetry data (COTAGA)

精确的海洋潮汐模型是至关重要的，因为（i）海洋潮汐的影响必须从CHAMP和GRACE观测中去除，以获得专门描述地球重力的重力场模型，以及（ii）高度海面高度应该是无潮汐的，以便相互比较并被同化到数值模型中。大陆架上和极地海洋中的海洋潮汐的定义是众所周知的，即使是最新的模型。因此，本项目的重点是两个战略：1）经验性的改进，以广泛使用的国家的最先进的海潮模型FES 2004（a）解决残差的主要潮汐成分的空间分辨率短至300公里的GRACE数据（长波长）和（B）应用响应和谐波分析多任务高度计数据，以估计特别是浅水区的校正为主的潮汐成分和非线性效应，如M4（短波长）。这两种校正都将得到验证，并与升级的FES 2004模型相结合，随后用于更精确地消除GRACE重力场模型的混叠，并改进测高数据的校正。这些调查将提供一个定量的动力潮汐模型，在公海和浅海进行同化，能够克服目前潮汐模型的缺陷。

Precise models of ocean tides are crucial because (i) the effect of ocean tides has to be removed from CHAMP and GRACE observations in order to obtain gravity field models describing exclusively the Earth gravity and (ii) altimetric sea surface heights should be ¿tidefree¿ in order to be comparable with each other and to be assimilated into numerical models. Deficiencies for ocean tides over continental shelves and in polar oceans are well known ¿ even for the most recent models. The present project therefore focuses on two strategies:1) Empirical improvements to the widely used state-of-the-art ocean tide model FES2004 by (a) solving residuals for major tidal constituents with a spatial resolution as short as 300 km from GRACE data only (long wavelength) and (b) applying response and harmonic analysis to multi-mission altimeter data to estimate in particular for shallow water areas corrections for the dominant tidal constituents and non-linear effect like M4 (short wavelength). Both, corrections will be validated and combined to an upgraded FES2004-model subsequently used for a more precise de-aliasing of the GRACE gravity field models and for improved corrections of altimetry data.2) Hydrodynamic modelling to further enhance the Hamburg Tide Model. Revising expertise these investigations shall provide a quantitative dynamical tide modelling with assimilation in open ocean and shallows sea, capable to overcome the deficiencies of current tide models.