|
|
|
| An Extension of the Dimension-Reduced Projection 4DVar |
| SHEN Si1,2, LIU Juan-Juan1, WANG Bin1,3 |
1State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049, China
3Ministry of Education Key Laboratory for Earth System Modeling, Center of Earth System Science (CESS), Tsinghua University, Beijing 100084, China |
|
|
|
|
Abstract This paper extends the dimension-reduced projection four-dimensional variational assimilation method (DRP-4DVar) by adding a nonlinear correction process, thereby forming the DRP-4DVar with a nonlinear correction, which shall hereafter be referred to as the NC-DRP-4DVar. A preliminary test is conducted using the Lorenz-96 model in one single-window experiment and several multiple-window experiments. The results of the single-window experiment show that compared with the adjoint-based traditional 4DVar, the final convergence of the cost function for the NC-DRP-4DVar is almost the same as that using the traditional 4DVar, but with much less computation. Furthermore, the 30-window assimilation experiments demonstrate that the NC-DRP-4DVar can alleviate the linearity approximation error and reduce the root mean square error significantly.
|
|
Received: 06 November 2013
Revised: 28 January 2014
Accepted: 19 February 2014
|
|
Corresponding Author:
LIU Juan-Juan
E-mail: ljjxgg@mail.iap.ac.cn
|
|
|
|
|
|
|
