张华,薛纪善,庄世宇,朱国富,朱宗申. 2004. GRAPeS三维变分同化系统的理想试验[J]. 气象学报, 62(1):31-41, doi:10.11676/qxxb2004.004
GRAPeS三维变分同化系统的理想试验
IDEA EXPERIMENTS OF GRAPES THREE-DIMENSIONAL VARIATIONAL DATA ASSIMILATION SYSTEM
投稿时间:2003-07-22  修订日期:2003-09-12
DOI:10.11676/qxxb2004.004
中文关键词:  三维变分同化  变量变换  预调节
英文关键词:Three-dimensional Variational assimilation  Variable transform  Preconditioning
基金项目:十五国家重点科技攻关计划项目(2001BA607B)“中国气象数值预报系统技术创新研究”
作者单位
张华 中国气象科学研究院数值预报研究中心, 北京, 100081 
薛纪善 中国气象科学研究院数值预报研究中心, 北京, 100081 
庄世宇 中国气象科学研究院数值预报研究中心, 北京, 100081 
朱国富 中国气象科学研究院数值预报研究中心, 北京, 100081 
朱宗申 中国气象科学研究院数值预报研究中心, 北京, 100081 
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中文摘要:
      文中介绍了一种新的、适合格点模式的三维变分同化方案GRAPeS-3DVAR。该方案采用相互独立的流函数、非平衡速度势函数、非平衡位势和水汽作为分析变量。通过变量变换对目标函数进行预调节,不仅避免了直接计算背景误差协方差逆矩阵的困难,而且改善了Hessian矩阵的性状,提高了收敛速度。采用EOF分解方法,将三维分析变量投影到垂直摸态上,分解成为二维场;水平方向采用数字(递归)滤波器代替矩阵运算,实现和简化了方案的求解。此外,还考虑了质量场和风场之间的平衡约束关系。理想试验结果表明,GRAPeS-3DVAR能够正确地反映多变量之间相互作用关系,收敛迅速,分析结果合理。
英文摘要:
      This paper introduces a new scheme of three-dimensional variational assimilation(GRAPeS-3DVAR), which is suitable for a grid-point model.The domain includes China area on horizontal dimension and 15 mandatory levels on vertical dimension.The scheme adopts stream function,unbalanced potential velocity,unbalanced geopotential heig htand humidity as analysis variables which are independent of each other.The cost function takes the way ofincremental method.To solve the problems that B-1 are il-conditioned and too large to be computed,the background termis preconditioned using a sequence of variable transform,which improves the convergence in the minimization process and avoids to calculate B-1 directly.EOF decomposition is used as vertical component of analysis variable transform to project onto vertical modes and separate each three-dimensional field into two-dimensional field.Recursive filters is used as horizontal component of analysis variable transform. LBF GS method is used on solution of optimization.Simple geostrophic balanced relationship is used.The system has passed verifications strictly and proved to be credibility.In order to test the functions of the system,A series ofidea experiments were made.The results showa reasonable relationship among the multi-variables and a fast convergence in the minimized process.
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