GRAPES_GFS中三维参考大气的研究:理论设计和理想试验  

A study on the three-dimensional reference atmosphere in GRAPES_GFS:Theoretical design and ideal test

作　　者：苏勇[1,2,3] 沈学顺 陈子通 张红亮[3] SU Yong;SHEN Xueshun;CHEN Zitong;ZHANG Hongliang(Department of Atmospheric Sciences, Nanjing University of Information ＆ Technology, Nanjing 210044, China;Chinese Academy of Meteorological Sciences, Beijing 100081, China;National Meteorological Center, Beijing 100081, China;State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China;Guangzhou Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou 510080, China)

机构地区：[1]南京信息工程大学大气科学学院,南京210044 [2]中国气象科学研究院,北京100081 [3]国家气象中心,北京100081 [4]中国气象科学研究院灾害天气国家重点实验室,北京100081 [5]中国气象局广州热带海洋气象研究所,广州510080

出　　处：《气象学报》2018年第2期241-254,共14页Acta Meteorologica Sinica

基　　金：国家重点研发计划项目(2017YFA0604500;2017YFC1501901)

摘　　要：参考大气的选取对于半隐式半拉格朗日(Semi-Implicit Semi-Lagrangian,简称SISL)模式动力框架的计算精度至关重要。中国气象局数值预报中心自主研发的GRAPES_GFS(Global Regional Assimilation and PrEdiction System,Global Forecast System)采用基于等温大气构造的一维参考大气,该方法求解简单、易于实现,但无量纲气压和位势温度扰动量的数量级较大,降低空间计算精度的同时,由于非线性项较大,使得时间计算精度较低。借鉴近年来世界上各主要业务中心的数值模式框架搭建方法,拟在GRAPES_GFS的动力框架中引入不随时间变化且满足静力平衡的三维参考大气,使得积分过程中参考大气可以尽量地靠近模式大气,提高空间计算精度的同时,减小非线性项的数量级,进而提高时间积分的计算精度。本研究重新推导了引入三维参考大气之后模式动力学方程组的求解过程,通过若干个理想试验验证了理论方法以及代码实现的正确性,说明新的三维参考大气可以有效地提高模式动力框架的计算精度。The selection of the reference profile is critical for the accuracy of the semi-implicit semi-Lagrangian dynamic core of atmospheric model.The GRAPES_GFS（Global Regional Assimilation and PrEdiction System,Global Forecast System）developed in the Numerical Weather Prediction Center of China Meteorological Administration is based on one-dimensional reference profile.While this method is simple and easy to realize,it reduces the accuracy of spatial computation due to large perturbations of dimensionless pressure and potential temperature.Meanwhile,the accuracy of time integration is also low because of the large nonlinear terms.In the present study,with reference to the method of constructing the dynamic core implemented in recent years in several major operational centers,a three dimensional reference profile that does not change with time and satisfies the hydrostatic balance is introduced into the dynamic core of GRAPES_GFS.The reference atmosphere can be as close as possible to the model atmosphere,which improves the accuracy of spatial computation and decreases the nonlinear terms and thus enhances the accuracy of time integration.This paper re-derives the process of solving the dynamic equations after introducing into the dynamic core the three-dimensional reference profile,and verify the results through a number of ideal tests.Results show that the new three-dimensional reference profile can effectively improve the computational accuracy of the dynamic core.The follow-up work will focus on the method of initialization for real-time forecast,and consecutive cycling forecast experiments will be conducted to evaluate the actual prediction performance of the new dynamic core.

关 键 词：GRAPES_GFS 参考大气 预估-修正 半隐式半拉格朗日 线性化 

分 类 号：P456.7[天文地球—大气科学及气象学]