使用2009年春季和夏季两个时段全国08时24h雨量观测资料,采取累积降水检验、平均误差和均方根误差分析方法,对用T213资料驱动WRF(WRF—T213)和用T639资料驱动WRF(WRF—T6391的预报进行评估检验和比较,并选择一次降水过程作对比分析。主要结果如下:WRF-T639部分雨量级的Ts评分有时略低于WRF—T213,但其空报率和系统偏差比WRF—T213小,从而使其预报效率和ETS评分均高于WRF—T213;分析24、48h的500hPa高度场、850hPa风场和海平面气压预报的平均误差及均方根误差发现,WRF—T639的形势场预报总体上优于WRF—T213;降水个例分析表明,WRF—T213预报的高压脊偏强,西南急流区以及有利的涡度场、散度场和垂直速度位置偏北,这导致其雨区偏北,WRF—T639对高度场、风场等的预报均优于WRF—T213,降水落区的预报和实况接近,其预报的地面低压偏强是造成雨量偏大的原因之一。
Using national 24 hour precipitation observation data at 8am in two time periods in spring and summer of 2009, the WRF forecasts driven by T213 and T639 data separately were verified and compared with methods of accumulated precipitation verification, mean error and root-mean-square error analysis, and a precipitation case was analyzed. The main results are as follows: though Ts score of WRF-T213 forecast at some rainfall grade was slightly higher than that of WRF-T639 sometimes, false alarm rate and system bias of WRF-T639 were less than that of WRF-T213, so that forecast efficiency and ETS score of WRF-T639 were higher than that of WRF-T213. The verification of 500hPa potential height field, 850hPa wind field and sea level pressure draws a conclusion that general circulation patterns prediction of WRF-T639 is better than that of WRF-T213. The rainfall case study shows that a stronger ridge, southwest jet stream, preferable vortieity field and divergence field and northerly position of vertical velocity forecasted by WRF-T213 result in the more northern position of the precipitation distribution. In conclusion, WRF-T639 has a better performance than WRF-T213 for 500hPa height field and 850hPa horizontal wind forecast, and its precipitation distribution forecast gets closer to observation. Stronger surface low pressure forecasted by WRF-T639 is one of the reasons for greater rainfall than observation.