模式湿物理过程的组合对一次南京大暴雨降水模拟的影响分析

The impact of combination of model moist physics process on numerical simulation of a Nanjing heavy rainfall event

以第五代中尺度模式(MM5)为基础,本文对一次南京大暴雨个例进行了三组数值模拟试验,研究了模式湿物理过程参数化方案的组合对梅雨暴雨降水预报的影响.试验结果表明:模式的积云对流参数化方案的选用对南京大暴雨的预报至关重要,积云对流参数化方案的选用比边界层参数化对暴雨数值预报的影响大;对20km模式分辨率而言,采用单一的积云对流参数化方案时,Betts-Miller方案占显著优势;模式粗、细网格采用不同的积云对流参数化方案进行组合,可以改进模式降水预报,对于60km/20km的二重嵌套网格来说,Anthens-Kuo and Betts-Miller或者Kain-Fritsch and Betts-Miller组合具有一定的优势.在此基础上,积云对流参数化方案与不同微物理过程组合可以进一步改进梅雨锋暴雨的预报,不同组合方案预报降水的中心位置和强度各不相同.另外,暴雨的分布、中心位置和强度对边界层参数化方案的选用表现出一定的敏感性.

In this paper,a series of numerical experiments are carried out on a Nanjing heavy rainfall case in the middle and lower reaches of Yangtze River（MLYR）.Using PSU/NCAR non-hydrostatic MM5,the impacts of model convection parameterization schemes（CPSs）,boundary layer parameterization（PBLs） and microphysics on the forecast of Nanjing heavy rainfall are discussed. The CPSs of model physics is more important to Meiyu heavy rainfall forecast in the MLYR than that of PBLs.As 20-km model resolution is concerned,the BM is predominated obviously when using a kind of CPSs.It is improved model precipitation forecast when the model is combinated with different CPSs in the coarse and fine meshes.To 60-km of the coarse domain and 20-km of the fine domain in two-way nest grids,the AK/BM or KF/BM have some predomination for Meiyu heavy rainfall forecast.The results of heavy rainfall forecast from different combination designs are different from each other.On the basis of such design,combination with different microphysics parameterization schemes can improve Mei-Yu front heavy rainfall forecast more.The distribution,central location and intensity of heavy rainfall are sensitive to the choice of PBLs also.