MCC降水过程集合预报不同物理过程扰动方案的对比试验研究

利用WRF模式,从模式的不确定性角度来构造中尺度的集合预报,重点对比分析了不同物理参数化方案、物理过程随机扰动方案、积云对流参数化敏感参数扰动方案对中尺度对流复合体降水集合预报的影响。试验结果表明:3种物理过程扰动方法都可以反映中尺度对流复合体降水预报的不确定性特征,其预报效果比控制预报好。物理过程随机扰动方案集合平均的降水落区及强度最接近实况,并且其降水的ETS评分要高于其他2种方案。从均方根误差与离散度的角度来看,3种方案中物理过程随机扰动的均方根误差要小于其他2种方案,而其离散度要大于其他2种方案,物理过程随机扰动方案要优于其他2种方案。

A comparative study of different physical process perturbation schemes for ensemble forecast on MCC system

The Weather Research and Forecasting(WRF) mesoscale numerical prediction model was used to construct mesoscale ensemble forecast from the aspects of model uncertainty.The focus was to compare and analyze the influence on precipitation forecast of mesoscale convection complex(MCC) exerted by the three methods,which were different physical parameterization method,the method of disturbing sensitive parameters in cumulus convection parameterization scheme and the stochastic physical perturbation method.The results showed that all of the three ensemble forecast methods could reflect the uncertainty of MCC precipitation forecast and they performed better than control forecast.Compared to the other two methods,the spatial distribution and intensity of ensemble mean 24-hour accumulated rainfall by stochastic physical perturbation method were closer to the reality.The 24-hour rainfall ETS of stochastic physical perturbation method was better than the other two methods.In terms of root mean square error (RMSE),the stochastic physical perturbation method had smaller RMSEs than the other two methods,while its dispersion was larger than the other two.In all,the stochastic physical perturbation method was superior to the other two methods.