2013年汛期ECMWF集合统计量产品的降水预报检验与分析

Precipitation verification and analysis of ECMWF ensemble statistic products in 2013 flooding season

2013年汛期ECMWF集合预报在江南、四川盆地和华北地区强降水过程中的表现如下:对江南和四川盆地强降水,概率匹配、融合产品、最大值、75%和90%分位数在大雨和暴雨预报中较确定性预报有明显正技巧,融合产品和90%分位数的技巧评分最稳定;对华北地区强降水,仅90%分位数在大雨预报中有一致的正技巧;上述统计量产品的中期预报技巧评分总体要高于短期预报,对四川盆地(华北地区)暖区强降水预报技巧评分总体要高(低)于对该区域锋面强降水预报技巧评分。根据概率匹配和融合产品各自特点,综合二者原理,设计出概率匹配-融合和融合-概率匹配两种新方案。结果显示,在暴雨和大暴雨降水预报中,融合-概率匹配的评分较融合产品有一定提高。

The main characteristics of the performance of ECMWF ensemble forecasts during several strong precipitation processes in regions south of Yangtze River, Sichuan Basin and North China in 2013 flooding season are summarized as follows. In regions south of Yangtze Riv- er and Sichuan Basin, compared with the deterministic forecasts, ensemble products, including probability matching, statistic fusing, maxi- mum, 75% and 90% quantile products, show positive skills in heavy and torrential rain forecasts. Overall, statistic fusing and 90% quantile products show the best performance. In North China, consistently positive skills are found only in 90% quantile products. As a whole, the skill scores of medium-range forecasts are higher than the ones of short-range forecasts for above-mentioned products. In addition, the fore- cast skill scores of warm area heavy rain are higher （lower） than the ones of fontal heavy rain in Sichuan Basin （North China） for these prod- ucts. Two new products, probability matching-fusing and fusing-probability matching, have been proposed in this paper, based on the char- acteristics and principles of probability matching and fusing products. The statistical results indicate that, the threat scores of fusing-probabili- ty matching are higher than fusing product for the rainstorm and heavy rainstorm forecasts.