王瑞春,龚建东,孙健. 2024. CMA-MESO公里尺度变分同化系统中极小化控制变量的重构[J]. 气象学报, (0):-, doi:[doi]
CMA-MESO公里尺度变分同化系统中极小化控制变量的重构
A reformulation of the minimization control variables in the CMA-MESO km-scale variational assimilation system
投稿时间:2023-05-14  修订日期:2023-11-27
DOI:
中文关键词:  CMA-MESO,公里尺度变分同化,控制变量,平衡约束
英文关键词:CMA-MESO, kilometer scale variational assimilation, control variables, balance constraint
基金项目:国家重点研发计划
作者单位邮编
王瑞春* 中国气象局地球系统数值预报中心 100081
龚建东 中国气象局地球系统数值预报中心 100081
孙健 中国气象局地球系统数值预报中心 100081
摘要点击次数: 27
全文下载次数: 18
中文摘要:
      重构GRAPES(Global/Regional Assimilation and Prediction System)全球区域一体化变分同化系统中的极小化控制变量,提升中小尺度同化分析能力,为中国气象局业务区域数值预报系统CMA-MESO提供公里尺度适用的同化方案。新方案采用纬向风速u和经向风速v替代原有流函数和势函数作为新的风场控制变量,采用温度和地面气压(T,ps)替代原有非平衡无量纲气压作为新的质量场控制变量,同时不再考虑准地转平衡约束,而是采用连续方程弱约束保证分析平衡。背景误差参数统计和数值试验结果表明,采用重构后的极小化控制变量,观测信息的传播更加局地,分析结构更加合理,避免了原方案在中小尺度应用时存在的虚假相关问题。而连续方程弱约束的引入,限制了同化分析中辐合辐散的不合理增长,帮助新方案在分析更加局地的同时保证分析平衡。为期一个月的连续同化循环和预报试验结果表明,新方案可以减小风场和质量场的分析误差,进而明显提高了CMA-MESO系统地面降水和10m风场的预报评分。
英文摘要:
      In order to improve the analysis capability of small- and medium-scale flows and to provide a kilometer-scale applicable assimilation scheme for the China Meteorological Administration(CMA) operational regional numerical weather prediction system CMA-MESO, a new formulation of the minimization control variables in the GRAPES (Global/Regional Assimilation and Prediction System) variational assimilation system has been developed. The new scheme uses eastward velocity u and northward velocity v to replace the original stream function and velocity potential as the new momentum control variables, and uses temperature and surface pressure (T, ps) to replace the original unbalanced dimensionless pressure as the new mass field control variable, and no longer introduces quasi-geostrophic balance constraint, but uses a weak mass continuity constraint to ensure analysis balance. The results of background error statistics and numerical experiments show that the adoption of the reformulated control variables results in a more local propagation of observational information and a more reasonable analysis, avoiding the spurious correlation problem of the original scheme when applied at small- and medium-scale analysis. The introduction of the weak mass continuity constraint suppresses the unrealistic convergence and divergence in the analysis, making the new analysis more balanced. The results of one-month assimilation cycle and forecast show that the new scheme could reduce the analysis errors in the wind and mass fields, which in turn significantly improves precipitation and 10m wind field forecast scores of the CMA-MESO system.
查看全文   查看/发表评论  下载PDF阅读器