对流凝结加热对华北夏季锋面影响的数值模拟研究

本文利用改进的ＭＭ２模式，用干、湿过程模拟了一次夏季华北锋面结构。干模式仅能模拟出大尺度特征和明显偏弱的锋面环流，而湿模式可模拟出某些重要的中尺度流场特征。表明只要具有合理的模式物理过程，使用大尺度资料，也可以在一定程度上模拟出中尺度系统。对流参数化的试验表明，系统演变和降水预报对湿润因子ｂ和增温廓线很敏感。在此工作基础上，设计了考虑下沉气流的积云参数化方案。初步结果表明，这种方案使降水量预报有改进。

A NUMERICAL SIMULATION OF THE CONVECTION HEATING EFFECT ON THE COLD FRONT IN NORTH CHINA DURING THE SUMMER SEASON

The modified NCAR/PSU mesoscale model version II (referred to as MM2) is used in this paper. First, the dry and moist version models simulate the structure of a cold front in North China during the summer season. The dry model only simulates the large scale features and the weaker frontal circulation. The moist case is capable of simulating some important features of the mesoscale stream fields. It indicated that if the large scale data is well initiallied and model has reasonal model physics processes , it also has the ability to simulate the mesocale features for some systems.The sensitivity tests of the cumulus parameterized scheme indicate that both the factor b of increasing humdity and the vertical heating profile are very sensitive to describing the evolution of system and to forecasting the precipitation. Based on above works, the cumulus parameterized scheme is designed, which includes the downdrafts.The preliminary results show that the new scheme improves the precipitation forecast.