CMA-GFS V4.0模式关键技术研发和业务化  

Key Model Technologies of CMA-GFS V4.0 and Application to Operational Forecast

作　　者：张进[1,2] 孙健 沈学顺[1,2] 苏勇[1,2] 马占山[1,2] 井浩[1,2] 刘奇俊[1,2] 张红亮 蒋沁谷 陈峰峰[1,2] 李喆[1,2] 金之雁 伍湘君[1,2] 梁妙玲[1,2] 刘琨 Zhang Jin;Sun Jian;Shen Xueshun;Su Yong;Ma Zhanshan;Jing Hao;Liu Qijun;Zhang Hongliang;Jiang Qingu;Chen Fengfeng;Li Zhe;Jin Zhiyan;Wu Xiangjun;Liang Miaoling;Liu Kun(CMA Earth System Modeling and Prediction Center,Beijing 100081;State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,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 [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：《应用气象学报》2023年第5期513-526,共14页Journal of Applied Meteorological Science

基　　金：国家自然科学基金重大项目(42090032)。

摘　　要：针对CMA-GFS V3.3强降水预报偏弱、西北太平洋副热带高压等天气系统预报衰减偏快以及模式计算效率偏低等问题,对模式物理过程与动力框架关键技术开展研发改进。在预报性能方面,通过在云微物理方案中增加霰粒子相关的微物理过程、调整蒸发速率,并在积云对流方案中改进触发条件、卷入率、准平衡闭合假定等关键因子的参数化方法,缓解模式强降水预报不足和小雨过多的问题;采用质量守恒修正算法解决模式长时间积分质量损失问题,改善天气形势预报。在计算效率方面,研制二维参考廓线方案延长模式积分时间步长,开发预条件经典斯蒂菲尔迭代(PCSI)算法提高Helmholtz方程的求解效率,对辐射方案、预估-修正算法等进行计算效率优化。通过上述关键技术的研发和应用,CMA-GFS在降水和天气形势方面的预报技巧得到显著提升,计算效率提高1/3左右,满足模式在0.125°分辨率下业务运行的时效要求,为CMA-GFS V3.3升级到V4.0奠定了基础。To address problems including underestimation of heavy precipitation,rapid decay of synoptic systems and low computational efficiency in operational forecast of CMA-GFS V3.3,some key technologies related to physics and dynamics of the model are developed and applied.A suite of graupel-related microphysical processes is adopted in the cloud microphysics scheme to improve the forecast performance of heavy precipitation.These processes include graupel colliding with cloud water,ice crystals and snow,automatic conversions of ice crystals to graupel and snow to graupel,melting process of graupel to raindrop and sublimation process of graupel.In addition,the evaporation rate of cloud and rainwater is restricted,which can increase the liquid water content in warm areas and improve precipitation efficiency.In the convection parameterization scheme,the role of the sub-cloud environmental relative humidity to convection triggers is considered,and the unreasonable occurrence of convections in dry environment is suppressed.Also,the sensitivity of the entrainment rate of the convective updraft to the relative humidity outside the cloud is enhanced to weaken the convections in dry environment.At the same time,the quasi-equilibrium closure scheme is optimized to improve the accuracy in calculating cloud-base mass flux which is related to the convection intensity.To solve the problem of the mass loss in long time integration,a mass conservation correction method is introduced to the model dynamic framework.The method is developed to ensure the mass conservation by adjusting mass in each grid box according to different weight coefficients which are determined by the change of total atmospheric mass of the current time step relative to the previous step.In terms of computational efficiency,the two-dimensional reference profile algorithm is developed.Without losing calculation accuracy,the model integration time step is extended from 240 s to 300 s using the new profile instead of the original three-dimensional reference profile.Me

关 键 词：CMA-GFS 云微物理 对流参数化 质量守恒修正 参考廓线 

分 类 号：P456.7[天文地球—大气科学及气象学]