GRAPES混合同化方法在青藏高原区域的初步试验  

A tentative experiment of GRAPES En-3DVAR hybrid data assimilation method over the Tibet Plateau

作　　者：夏宇[1] 陈静[2] 刘艳[2] 朱克云[1] 陈良吕 袁月[1] XIA Yu;CHEN Jing;LIU Yan;ZHU Keyun;CHEN Lianglyu;YUAN Yue(Chengdu University of Information Technology,Chengdu 610025,China;Numerical Weather Prediction Centre,Beijing 100081,China;Chinese Academy of Meteorological Sciences,Beijing 100081,China)

机构地区：[1]成都信息工程大学,四川成都610225 [2]中国气象局数值预报中心,北京100081 [3]中国气象科学研究院,北京100081

出　　处：《大气科学学报》2018年第2期239-247,共9页Transactions of Atmospheric Sciences

基　　金：国家自然科学基金资助项目(41075035);国家重点基础研究发展计划(2012CB417204)

摘　　要：针对青藏高原地区气象观测站点稀少和模式同化分析质量较低的问题,将GRAPES区域集合变分(En-3DVAR)混合同化系统应用于青藏高原地区,进行了单点理想试验和真实观测资料同化分析预报试验,分析评估青藏高原混合同化分析增量及预报误差的水平垂直结构特征及其合理性,并与中国东部平原地区进行比对。单点理想试验表明,En-3DVAR混合同化系统中背景误差协方差具备流依赖属性。真实资料混合同化试验结果表明,基于集合预报估计的分析增量具有流依赖的特征,特别是在高原地区和槽脊系统附近;青藏高原地区分析场的绝对误差总体低于3DVAR系统,其平均绝对误差在中层和高层低于平原地区,说明在青藏高原地区的改进效果略优于平原地区。需要关注的是,青藏高原地区En-3DVAR混合同化分析增量总体大于3DVAR,特别是近地面层u风分量分析增量明显偏大,这可能与青藏高原复杂地形有关。In view of the sparse observation stations and low quality of the model analysis in the Tibet Plateau,the Ensemble-3DVAR hybrid data assimilation system(En-3DVAR)is used and both a single pressure observation data assimilation experiment and an assimilation analysis and prediction experiment based on real observation data are conducted.The experiments are to analyze and evaluate the horizontal and vertical structure and rationality of En-3DVAR hybrid assimilation analysis increment over the Tibetan Plateau and to compare them with the data in plain area in Eastern china in order to improve the quality of the data assimilation analysis field in the Tibet Plateau and to improve the model by using the En-3DVAR hybrid assimilation method.The single pressure observation data assimilation experiment shows that the background error covariance of En-3DVAR has the characteristic of flow-dependence.The real data En-3DVAR hybrid assimilation experiment shows that the analysis increment based on ensemble forecast has the characteristic of flow-dependence,especially in the Tibet Plateau and near trough and ridge systems.The absolute error of the analysis field in the Tibet Plateau is generally lower than that of 3DVAR system and the mean absolute error of the analysis field in the Tibet Plateau is lower than that in the plain area on the middle and high levels.The result shows that the improvement effect in the Tibet Plateau is better than that in plain area.What is worth our attention is that in the Tibet Plateau the analysis increment of the En-3DVAR hybrid assimilation is generally larger than that of 3DVAR.Especially on the surface layer,the u-wind component analysis increment is obviously much larger than 3DVAR,which may be related to the complex terrain of the Tibet Plateau.

关 键 词：GRAPES 青藏高原 混合同化方法 初步试验 

分 类 号：P412[天文地球—大气科学及气象学]