Nonlinear balance constraints in 3DVAR data assimilation
Nonlinear balance constraints in 3DVAR data assimilation
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DOI：
10.1007/s11430-006-0331-7
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发表时间：
2006-03
影响因子：
5.7
通讯作者：
Zhu Jiang;Chang-xiang Yan
中科院分区：
文献类型：
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作者：
Zhu Jiang;Chang-xiang Yan
在3DVAR的许多应用中，平衡约束可以通过两种主要方法来考虑：弱约束方法，在成本函数中添加惩罚项；以及具有非零互相关子矩阵的背景误差协方差矩阵的正确定义。弱约束方法需要确定惩罚项的权重矩阵。背景误差协方差方法不需要确定那些额外的加权矩阵。然而，它仅适用于那些线性或线性化平衡约束。通过推广所谓的 Derber-Bouttier 公式，基于背景误差协方差方法提出了一种新方法。通过海面动态高度观测估计温度和盐度的同化实验来说明非线性平衡约束的处理方法。
In many applications of 3DVAR, the balance constraints can be considered via two main approaches: weak constraint method which adds penalty terms to the cost function; and proper definition of the background error covariance matrix with non-zero cross-correlation sub-matrices. The weak constraint approach requires determining the weighting matrices of the penalty terms. The background error covariance approach does not require determining those additional weighting matrices. However, it is only applicable to those linear or linearized balance constraints. A novel approach is proposed based on the background error covariance approach by generalizing the so-called Derber-Bouttier formulation. An assimilation experiment of estimating temperature and salinity from the sea surface dynamic height observation is given to illustrate the proposed treatments of nonlinear balance constraints.