三个数值模式对四川省2022年汛期降水检验评估

Evaluation of Three Numerical Models for Precipitation in Sichuan Province during the 2022 Flood Season

  • 摘要: 采用传统统计检验和精细化检验方法,基于CMA-MESO、CMA-GFS和ECMWF三个模式对四川省2022年汛期降水开展检验评估,比较三个模式降水预报性能优势和偏差特征,并依据地形和气候特征差异将全省分成四川盆地、边坡区域、攀西地区和川西高原,分别对其进行检验评估。结果表明:(1)就四川整体而言,CMA-MESO模式晴雨预报和大暴雨最优,CMA-GFS模式暴雨和大暴雨预报性能最差、漏报最多,ECMWF模式优势在中雨、大雨和暴雨预报上。(2)从不同区域看,CMA-MESO模式各级降水预报在攀西地区均为最优,CMA-GFS模式晴雨预报在边坡地区最优,ECMWF模式中雨预报在各区域均表现优异,但对攀西和川西大暴雨基本无预报能力。(3)随着预报时间延长,CMA-MESO和CMA-GFS模式都存在预报性能降低的现象,临近时次起报的预报结果中空报和漏报有所减少,模式对高频发生事件预报更为稳定,小概率事件预报结果随机性较强。(4)CMA-MESO模式预报的平均降水量和降水强度变化趋势与实况最为近似,但夜间峰值偏大较多,CMA-GFS模式每日世界时12时起报的川西高原平均降水量和降水强度预报较优,ECMWF模式预报的降水频率与实况偏差最大,降水频率峰值出现在白天而实况则在夜间。

     

    Abstract: Using traditional statistical verification methods and refined verification methods, the precipitation in Sichuan during the 2022 flood season was evaluated based on the CMA-MESO, CMA-GFS, and ECMWF, the performance advantages and bias characteristics of the three models were compared. Furthermore, based on differences in topography and climate, the province is divided into four sub-regions for separate assessment: the Sichuan Basin, the Border Slope region, the Panxi region, and the Western Sichuan Plateau. The results show that: (1) For the province-wide precipitation, the CMA-MESO model shows the best performance for clear/rainy day forecasts and heavy rainstorm forecasts. The CMA-GFS model performs the worst for rainstorm and heavy rainstorm forecasts, with the highest omission rates. The ECMWF model excels in forecasting moderate rain, heavy rain, and rainstorms. (2) For the sub-regional precipitation, the CMA-MESO model delivers the best forecasts for all precipitation grades in the Panxi region. The CMA-GFS model performs best for clear/rainy day forecasts in the Border Slope region. The ECMWF model demonstrates superior performance for moderate rain forecasts in all regions but shows essentially no forecasting skill for heavy rainstorms in the Panxi and Western Sichuan Plateau regions. (3) With the prolongation of forecasting time, both the CMA-MESO and CMA-GFS models exhibit a decline in performance. Forecasts initiated at shorter lead times show reduced false alarms and misses. The models are more stable in forecasting high-frequency events, whereas forecasts for low-probability events are more random. (4) The trend in average precipitation and precipitation intensity in the CMA-MESO model is most similar to that of the actual situation, but the peaks at nighttime are larger. The CMA-GFS model is better in predicting the average precipitation and precipitation intensity in the Western Sichuan Plateau when initialized at 12 UTC. The ECMWF model shows the largest deviation in forecasted precipitation frequency from observations, with the peaks occurring during the daytime while the actual situation is at nighttime.

     

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