一次特大暴雨天气的数值模拟试验研究

目的检验各非绝热物理过程参数化方案对模式输出结果的影响,进一步了解和认识MM5模式中不同积云对流参数化方案的性能、特点和适用范围,为合理选择使用模式中的物理过程参数化方案提供依据,提高模式对类似暴雨天气过程的预报能力。方法运用相互比较和试验分析的方法在不同模式分辨率下,对MM5V3模式中的不同物理过程参数化方案设计18种组合方案,进行比较试验和分析。结果主要雨带位置对参数化方案并不是十分敏感,但模拟的暴雨中心强度、范围、雨带走向随参数化方案的不同有较大变化,甚至出现虚假的强降水中心。各组合方案模拟的天气尺度系统水平环流结构差别较小,模拟的中尺度系统结构存在着较大差别,这种差别对定点、定量降水的准确预报产生影响。结论在实际预报中可根据初始气象场的分型特点选择较合适的组合方案启动数值预报模式,从而达到提高模式对类似暴雨天气过程的预报能力。

The effect of the coupling schemes of different physical processes on a mesoscale heavy rainfall simulation

Aim To implement more sophisticated adiabatic physical processes into mesoscale numerical weather predication models,which is helpful to understand the properities,characterastics of cumulus parameterization schemes in the weather forcast.Methods Based on the Mesoscale Model version 5(MM5) and the data sets of one heavy rainfall,the effect of 18 coupling schemes of four physical processes including cumulous parameterization scheme,planetary boundary layer scheme,radiation parameterization schemes and explicit cloud physics schemes on mesoscale heavy rain simulation are investigated,with deeply analyzing the impact of the four physical processes on dynamic and thermodynamic element predictions of heavy rain.Results The result show that the coupling scheme 1 to the coupling scheme 3 has the better effect on the short-range forecast of the heavy rain,and the coupling scheme 1 is the best one.The coupling scheme MM5 model can successfully simulate the rainstorm and the development of the mesoscale system.The radiation scheme has more impacts on heavy rain than planetary layer scheme,cumulous convection scheme and explicit cloud physical schemes.The physical processes have less impact on the short-range forecast of the structure of synoptic scale system,but have more impact on the short-range forecast of mesoscale structure.Conclusion It is important to select physical schemes to run the umerical model in the weather forcast,so as to enhance the prediction capability for this kind of heavy rain.