不同分辨率对淮河流域连续暴雨过程影响的中尺度模拟试验

利用NCAR 和NOAA 发展的新一代中尺度模式WRF(Weather Research and Forecast),对2003年7 月上旬发生在我国淮河流域三个连续暴雨过程(7 月1—11 日)进行了数值模拟试验,研究的重点是了解不同水平分辨率(45、30、20 和10 km)对WRF 模拟结果的影响。模拟结果与观测的比较表明,WRF 模式能够合理地模拟不同时段的降水带以及平均环流形势的分布特征,对于区域平均等压面上的物理量也有较好的模拟性能。不同分辨率的模拟结果比较表明:不同分辨率对降水的模拟效果影响较大,提高模式水平分辨率有助于预报效果的改善,但高分辨率模拟的降水强度偏强,空报偏多;不同分辨率对环流形势的模拟效果影响不大,各个分辨率的低层风场误差都存在一个5～6 天的波动,并向模式的中高层传播,传播速度约为3 天。 

MESOSCALE SIMULATION OF A HEAVY RAINFALL IN THE HUAIHE RIVER VALLEY IN JULY 2003: EFFECTS OF DIFFERENT HORIZONTAL RESOLUTIONS

Numerical simulation experiments have been conducted with the Weather Research and Forecast(WRF) model with different horizontal resolutions and physical parameterization schemes to investigate the effects of resolution on the model performances in reproducing a abnormally prolonged heavy rainfall process in the Huaihe river valley in early July 2003(1st—11th). This paper focuses on the resolution impact on the simulation results.The comparisons between the model results with different resolutions(45 km,30 km,20 km and 10 km) and observations have indicated that the model has a basic and reasonable reproduction of the rainfall belt,the circulation characteristics over different periods,as well as the regional mean variables.The performance of rainfall simulation improves significantly with increased horizontal resolution,but that of circulation modeling is not affected as much.The errors of modeled wind in the model low levels all have the characteristics of fluctuation and propagate to the upper lever at the same time.