贵州冬季静止锋层状云小降水过程WRF模式预报中云内湍流参数化研究

Study on cloud turbulence parameterization in WRF model forecast of small precipitation process within winter stationary front in Guizhou

降雨是影响环境空气质量的重要影响因素,提高降雨预测准确性对环境空气质量预报具有重要意义,但WRF模式对于贵州冬季层状云小降水的模拟能力较差。本研究以贵州省贵阳市为例,在WRF气象场数值预报的基础上研究静止锋暖云降水过程云物理参数和降水的关系,从而建立静止锋暖云降水过程的模式参数订正回归关系。模式计算结果表明,在对WRF模式进行云层厚度、云底高度、气层最大相当位温等常规参数设置的基础上,调整云内湍流强度的理查逊数(R_(i))可使降水预测准确率得到提高。不同湍流状态下参数化订正比整体订正的效果更好,尤其在中上部湍流不稳定情况下,参数化订正能大幅提高模式预报降水的准确率。

Precipitation is an important factor affecting ambient air quality,and it is of great significance to improve the accuracy of rainfall prediction for ambient air quality prediction.However,WRF model has poor ability to simulate small precipitation in winter stratiform cloud in Guizhou province.In this study,Guiyang city of Guizhou Province is taken as an example to explore the relationship between cloud physical parameters and precipitation in the warm cloud precipitation process of stationary front based on the numerical forecast of WRF meteorological field,to establish the revised regression relationship of model parameters of stationary front warm cloud precipitation process.The results of model calculation show that the accuracy of precipitation prediction can be improved by adjusting the R ichardson number(R_(i))of turbulence intensity in cloud based on the presetting of conventional parameters such as cloud thickness,cloud base height and maximum equivalent temperature of gas layer.Especially in the middle and upper turbulent instability,parametric correction could greatly improve the precipitation prediction performance of the model.