An application of the A-4DEnVar to coupled parameter optimization

作     者：Yantian Gong Kangzhuang Liang Xinrong Wu Qi Shao Wei Li Siyuan Liu Guijun Han Hanyu Liu Yantian Gong;Kangzhuang Liang;Xinrong Wu;Qi Shao;Wei Li;Siyuan Liu;Guijun Han;Hanyu Liu

作者机构：School of Marine Science and TechnologyTianjin UniversityTianjin300072China Key Laboratory of Marine Environmental Information TechnologyNational Marine Data and Information ServiceMinistry of Natural ResourcesTianjin300171China Tianjin Key Laboratory for Oceanic MeteorologyTianjin300074China 

出 版 物：《Acta Oceanologica Sinica》 (海洋学报（英文版）)

年 卷 期：2022年第41卷第9期

页      面：60-70页

核心收录：

学科分类：07[理学] 070601[理学-气象学] 0706[理学-大气科学] 

基　　金：The National Key Research and Development Program under contract No.2021YFC3101501 the National Natural Science Foundation of China under contract No.41876014 

主　　题：4D-Var A-4DEnVar coupled parameter optimization “twin”experiments 

摘      要：In variational methods,coupled parameter optimization(CPO) often needs a long minimization time window(MTW) to fully incorporate observational information,but the optimal MTW somehow depends on the model *** analytical four-dimensional ensemble-variational(A-4DEnVar) considers model nonlinearity well and avoids adjoint *** can theoretically be applied to *** verify the feasibility and the ability of the A-4DEnVar in CPO,“twin experiments based on A-4DEnVar CPO are conducted for the first time with the comparison of four-dimensional variational(4D-Var).Two algorithms use the same background error covariance matrix and optimization algorithm to control *** experiments are based on a simple coupled oceanatmosphere model,in which the atmospheric part is the highly nonlinear Lorenz-63 model,and the oceanic part is a slab ocean *** results show that both A-4DEnVar and 4D-Var can effectively reduce the error of state variables through ***,two methods produce almost the same results in most cases when the MTW is less than 560 time *** results are similar when the MTW is larger than 560 time steps and less than 880 time *** largest MTW of 4 D-Var and A-4DEnVar are 1 200 time ***,A-4DEnVar is not sensitive to ensemble size when the MTW is less than 720 time steps.A-4DEnVar obtains satisfactory results in the case of highly nonlinear model and long MTW,suggesting that it has the potential to be widely applied to realistic CPO.