预估-校正的半隐式半拉格朗日时间积分方案及其在CMA-GFS模式中的应用  

A semi-implicit semi-Lagrangian time integration schemes with a predictor and a corrector and their applications in CMA-GFS

作　　者：张红亮[1,2] 沈学顺[1,2] 苏勇[1,2] ZHANG Hongliang;SHEN Xueshun;SU Yong(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]中国气象局地球系统数值预报中心,北京100081 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081

出　　处：《气象学报》2022年第2期280-288,共9页Acta Meteorologica Sinica

基　　金：国家重点研发计划项目(2017YFC1501901、2018YFC1505705)。

摘　　要：CMA-GFS采用的是传统的二时间层半隐式半拉格朗日时间积分方案(SISL)。拉格朗日平流速度和非线性项需要采用时间外插进行计算,在急流轴附近等梯度大值区会造成计算不稳定,甚至积分中断现象。文中通过构造预估-校正半隐式半拉格朗日时间积分方案(SISL/P-C),以减少时间外插的影响;半隐式系数由原来的0.72减小到0.55,构造准二阶精度的时间积分方案。理想试验和实际资料试验证明新方案可以改善CMA-GFS的精确度、稳定性和质量守恒。0.25°水平分辨率下积分时间步长可以由300 s增大到450 s,模式总体计算效率提高20%。A classical two-time level semi-implicit semi-Lagrange scheme(SISL) is used in CMA-GFS. Lagrange advection velocity and nonlinear terms are calculated by temporal extrapolation, which can cause computational instability and even integration interruption in large gradient areas such as the areas of jet. A SISL/P-C(predictor-corrector) algorithm is developed in CMA-GFS to reduce the impact of temporal extrapolation and construct a quasi-second order precision time discretization scheme by reducing the semi-implicit coefficients from 0.72 to 0.55. Results of idealized and real-data experiments show that this new scheme can effectively improve forecast accuracy, stability and conservation. The integration time step can be increased from 300 s to 450 s at 0.25°horizontal resolution, and the model calculation efficiency can be increased by 20%.

关 键 词：预估-校正法 二时间层半隐式半拉格朗日方案 CMA-GFS 

分 类 号：P435[天文地球—大气科学及气象学]