The ongoing transition to coupled data assimilation (DA) systems encounters substantial technical difficulties associated with the need to merge together different elements of atmospheric and ocean DA systems that typically have had independent development paths for decades. In this study, we consider the incorporation of strong coupling in the observation space via successive corrections that involve the application of only uncoupled solvers to a sequence of innovation vectors. The coupled increment is then obtained by projecting a coupled innovation vector on the grid using coupled ensemble correlations. The proposed approach is motivated by the classic block Jacobi matrix iteration applied to the coupled system using the uncoupled solvers as a preconditioner. The method is tested via numerical experiments with the CERA ensemble in a simplified setting.

中文翻译：

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强耦合数据同化中的块迭代校正

向耦合数据同化 (DA) 系统的持续过渡遇到了与需要将大气和海洋 DA 系统的不同元素合并在一起的重大技术困难，这些 DA 系统通常具有独立的发展路径数十年。在这项研究中，我们考虑通过连续修正将强耦合纳入观测空间，这些修正涉及仅将解耦求解器应用于一系列创新向量。然后通过使用耦合系综相关性在网格上投影耦合创新向量来获得耦合增量。所提出的方法是由应用于耦合系统的经典块雅可比矩阵迭代推动的，使用非耦合求解器作为预处理器。