CMA-MESO 3 km模式中自适应时间步长方案试验  

Experiment on Adaptive Time Step Scheme in CMA-MESO 3 km Model

作　　者：邓莲堂[1] 朱立娟[1] 张进[1] 于翡[1] DENG Liantang;ZHU Lijuan;ZHANG Jin;YU Fei(CMA Earth System Numerical Prediction Center,Beijing 100081)

机构地区：[1]中国气象局地球系统数值预报中心,北京100081

出　　处：《气象科技》2025年第1期10-21,共12页Meteorological Science and Technology

基　　金：国家重点研发计划(2022YFC3004102);河南省重大科技专项(201400210800)共同资助。

摘　　要：时间步长是数值天气模式稳定运行的关键参数。为实现业务模式稳定运行并保证运行效率,根据CMA-MESO 3 km模式时间积分方案特点,设计了自适应时间步长方案。以模式最大库朗数为依据,提出瞄准法和削顶法两种方法。根据CMA-MESO模式动力框架特点,研发了相应时间控制技术并在CMA-MESO 3 km系统中程序实现了自适应时间步长方案。个例和批量试验结果显示,采用瞄准法,模式中最大库朗数会在目标值附近变化,使模式更加稳定。采用削顶法,会调整模式中最大库朗数超出目标值的部分,保证模式稳定积分的同时,又尽量少地干预模式。总之,两种方法的自适应时间步长方案能够有效避免模式积分溢出情况,显著地提高模式的稳定性。对于3 km分辨率的模式来说,当库朗数目标值取1.2左右时,削顶法比瞄准法更适合业务运行。目前,自适应时间步长方案已投入业务应用。The time step is a critical parameter for the stable operation of numerical weather models.To achieve stable model operation and ensure efficiency,an adaptive time step scheme is designed based on the characteristics of the time integration scheme of the CMA-MESO 3 km model.This scheme relies on the model’s maximum Courant number and proposes two methods:the target aiming method and the top trimming method,depending on the adjustment approach.(1)Target aiming method:after adjusting the model’s time step,the maximum Courant number in the model approaches a given target value throughout the entire integration process.(2)Top trimming method:after adjusting the model’s time step,the maximum Courant number in the model does not exceed a given target value throughout the entire integration process.In order to implement the adaptive time step scheme in the CMA-MESO 3 km model,time control technology suitable for the CMA-MESO 3 km model is developed,including time control for the integration process,time processing for input/output,and time interpolation handling.Two types of experiments,namely case experiments and batch experiments,are designed to verify the application performance of the scheme in the CMA-MESO 3 km model.The individual case experimental results show that when the target aiming method is employed,the maximum Courant number in the model fluctuates around the target value,enhancing model stability.As the target Courant number decreases,the model becomes more stable,but the total number of integration steps and the total integration time increase.When using the top trimming method,adjustments to reduce the time step are only made when the maximum Courant number in the model exceeds the target value,keeping the maximum Courant number close to the target.When the Courant number is below this target value,if the model’s time step has been previously adjusted,the time integration step is gradually restored to the initial time step;otherwise,the model’s time step remains unchanged.The results of batch

关 键 词：CMA-MESO 自适应时间步长 瞄准法 削顶法 

分 类 号：P456.7[天文地球—大气科学及气象学]