基于TIGGE多模式的6 h降雨预报精度对比分析

A comparative analysis of the 6 h rainfall forecast accuracy based on TIGGE multi-model

  • 摘要: 降雨数值预报是预防极端天气导致灾害事件的重要手段,其预报精度是预报产品是否被采用的依据。以跋山水库流域为研究对象,选取了TIGGE系统中的ECMWF、NCEP、CMA、JMA、UKMO共5个预报模式的控制预报与集合预报,分别从降雨分级预报检验和降雨量预报检验两个角度,利用Brier评分和Talagrand分布图,分析了2007—2019年5—9月控制预报和集合预报降雨数据的精度。结果表明:(1)就降雨分级预报而言,对于无雨、小雨和中雨量级,5个预报模式控制预报和集合平均预报效果相差不大;对于大雨量级,JMA和NCEP的控制预报效果最佳,JMA和UKMO的集合平均预报效果最佳;对于暴雨及以上量级,NCEP的控制预报和集合平均预报均效果最佳;(2)针对降雨量预报,UKMO控制预报和集合平均预报效果最佳;(3)无雨等级的Brier评分最高,且Brier评分随着降雨等级的提升而降低,表明大量级降雨时Brier评分较好;CMA的评分在无雨、小雨、中雨、大雨4个等级表现最好;(4)5个模式Talagrand分布形态均呈粗略的“U”字型,表明5个预报模式集合成员的分散不够。综合来看,UKMO和NCEP的预报效果最佳。据此研究可选出高精度的降雨预报产品。

     

    Abstract: Numerical forecast of rainfall is an important means to prevent disasters caused by extreme weather, and its forecast accuracy is the basis for the application of forecasting products. In this study, taking the Bashan Reservoir watershed as the research object, the control forecast and ensemble forecast of ECMWF, NCEP, CMA, JMA and UKMO in TIGGE are selected. From the view of rainfall classification forecast test, rainfall forecast test, as well as Brier score and Talagrand distribution, the accuracy of control rainfall forecast and ensemble rainfall forecast from May to September in 2007 to 2019 is analyzed. The results show that: (1) For the rainfall classification forecast, there is a little difference between the control forecast and the ensemble average forecast of the five forecasting models for the no rain, light rain and moderate rain; for the heavy rainfall, the control forecast accuracy of JMA and NCEP is the best, and the ensemble average forecast accuracy of JMA and UKMO is the best; for the heavy rain and above, the control forecast accuracy and ensemble average forecast accuracy of NCEP are the best. (2) For rainfall forecast, the control forecast accuracy and ensemble forecast accuracy of UKMO are the best. (3) The Brier score of no rain is the largest, and with the increase of rainfall grade, the Brier score decreases, indicating that the Brier score is better in extreme weather; the Brier score of CMA is the best in the no rain, light rain, moderate rain and heavy rain. (4) The Talagrand distributions of the 5 forecasting models all show a rough “U” shape, indicating that the ensemble members of the 5 forecasting models are not dispersed enough. Generally speaking, the forecasting accuracy of UKMO and NCEP is the best. Based on this study, high-precision rainfall forecasting products can be selected.

     

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