基于GRAPES-MESO模式的极端短时强降水预报

Extreme Short-time Heavy Precipitation Forecast Based on GRAPES-MESO Model

利用2017—2018年5—9月四川盆地109个自动站逐小时降水资料,以及GRAPES-MESO模式0.1°×0.1°的逐3 h预报场资料,从热力不稳定、水汽、动力条件等方面分析极端短时强降水(1 h降水量大于等于50 mm)发生发展所需的关键物理量指标,结合随机事件概率思想和主成分分析方法构建预报模型,研发极端短时强降水概率预报产品。经预报效果评估,当概率值达0.7以上时,TS评分为24.0%,可将其作为极端短时强降水预报的参考阈值。2019年7月22日四川盆地暴雨过程应用表明,该产品对极端短时强降水落区有较好的参考意义。

Based on hourly precipitation data from 109 meteorological stations in Sichuan basin and 3-hourly forecast data with 0.1°×0.1°spatial resolution from GRAPES-MESO model from May to September during 2017-2018,this study investigated the characteristic of key physical parameters of the occurrence and development of extreme short-time heavy precipitation(hourly precipitation amount≥50 mm),such as thermal instability,water vapor and dynamic conditions.A prediction model was established using random probability thought and principal component analysis method to develop the extreme short-time heavy precipitation probability forecast product.The forecast effect evaluation showed that the TS was 24.0%when the probability was greater than or equal to 0.7.The value could be used as the reference threshold for the extreme short-time heavy precipitation forecast.During the rainstorm process in Sichuan basin on 22 July 2019,the practical application indicated that the product had good reference meaning for the forecast of extreme short-time heavy precipitation location.