Implementation of CMA-GFS 3D-Var System on the Yin-Yang Grid  

作　　者：ZHUANG Zhao-rong XUE Ji-shan SHEN Xue-shun LI Xing-liang 庄照荣;薛纪善;沈学顺;李兴良(CMA Earth System Modeling and Prediction Centre,Beijing 100081 China;State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081 China)

机构地区：[1]CMA Earth System Modeling and Prediction Centre,Beijing 100081 China [2]State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081 China

出　　处：《Journal of Tropical Meteorology》2021年第4期346-354,共9页热带气象学报（英文版）

基　　金：National Key R&D Program of China(2017YFC1501901,2017YFA0603901)。

摘　　要：The global three-dimensional variational(3D-Var)data assimilation is implemented on a new quasi-uniform overset(Yin-Yang)grid on sphere.As a quasi-uniform spherical grid,it covers the sphere by overlapping two perpendicularly oriented grid components which is nothing but low latitude region of the usual latitude-longitude grid.Based on this characteristic of the Yin-Yang grid,it enables us to implement the regional 3D-Var system efficiently and accurately on the Yin or Yang component grid,respectively.The global analysis could update directly from the regional analysis since they have the same configurations like the precondition of eigenvalue decomposition for vertical direction,recursive filtering for horizontal direction,minimization method and observation operator and so on.However,the balance equation and vector wind are needed to be paid more attention on the Yin grid analysis due to its coordinate transformation.How to spread the observation information near the boundary of Yin and Yang grid is a key to the 3D-Var analysis.Extending double the horizontal correlation length distance in the overset boundary of Yin and Yang grid has successfully solved the problem.The results show that the analysis on the Yin-Yang grid is reasonable and similar to the result on the latitude-longitude(LAT-LON)grid.This paper provides a promising strategy for the development of a 3D-Var global system for overset grids.

关 键 词：Yin-Yang grid latitude-longitude grid CMA-GFS regional 3D-Var global 3D-Var 

分 类 号：P456.7[天文地球—大气科学及气象学]