藉物理耗散技术改进强降水数值模拟的初步研究

利用PSU/NCAR非静力中尺度模式MM5V3,对影响我国北方一次非汛期突发性强降水过程实例,进行了三重嵌套模式区域采用若干不同降水方案(特别是采用显式微物理方案与积云对流参数化方案若干组合)的对比试验,在揭示物理耗散技术正是通过将模式水平扩散方案纠正到符合热力学第二定律的约束而使该中尺度模式的模拟精度和模拟质量获得明显提高的物理实质的同时,从一个侧面证实了数值模式引入第二定律对提高数值天气预报准确率的重要性。

An Attempt in Improving Numerical Simulation of Severe Precipitation Via the Physical Dissipative Technique

The numerical comparative experimentson sensibility of the physical dissipative technique to precipitation parameterizations,esp.to the different combinations of the explicit micro-physical schemes and cumulous convection parameterizations,in the PSU/NCAR meso-scale model MM5V3 with a triple-nested domain is conducted using the case of heavy rain occurredin the North China in October 2003.The experiments reveal some meaningful results,notably the dramatic improvement in the simulative accuracyand quality by thephysical dissipative technique based on the second law of thermodynamics resulting from modifying the direction of horizontal diffusion in the model into the correct one.On the other hand,the weak sensibility of the physical dissipative technique to the schemes of parameterization,as shown by the comparative experiments,is mainly because improving the field of rainfall by the physical dissipative technique is reached via improving the outputs of the model variables such as wind field determining the divergence field that is one of the most important factors when designing the schemes of precipitation parameterization.