ECMWF模式降水预报能力在重庆地区的检验评估

Test and Evaluation of ECMWF Model Precipitation Forecast Capability in Chongqing

  • 摘要: 欧洲中期天气预报中心(ECMWF)模式是业务预报中广泛采用的数值模式之一。利用2017—2019年ECMWF模式对重庆地区的降水预报数据及实况数据,采用TS评分、ETS评分、空报率、漏报率、预报偏差等对模式预报能力进行全面分析评估。结果显示:随着降水量级增大和预报时效的延长,TS评分、预报偏差和ETS评分呈现下降趋势,而漏报率、空报率则呈现上升趋势;不同降水量级,TS评分和ETS评分的年变化特征明显不同,除了暴雨及以上级别外,其余降水量级在8月两个评分值最低,秋季预报能力相对较强;在季节变化方面,降水落区和降水量的预报偏差明显,冬季偏差最大,秋季偏差最小,不同预报时效中,24 h预报表现最优;年平均日降水量的分布整体表现为预报偏小,在重庆西部和东北部偏差尤其明显;分析雨季降水过程发现,模式能够较好地捕捉降水过程的不同阶段,24 h预报与降水实况最接近。

     

    Abstract: The European Centre for Medium-Range Weather Forecasts (ECMWF) model is a prominent numerical model extensively utilized in operational meteorological forecasting. Using ECMWF model precipitation forecast data and observed data for Chongqing from 2017 to 2019, a comprehensive analysis and evaluation of the model's forecasting capability was conducted using TS score, ETS score, false forecast rate, missing forecast rate, and BIAS. Our findings indicate a pronounced decline in TS, ETS, and BIAS as precipitation intensity and forecast lead time escalate. Conversely, the false forecast rate and missing forecast rate demonstrate a significant increase. The annual variation characteristics of the TS and ETS scores are significantly different for different precipitation levels. Except for heavy rainfall and above levels, the scores of other precipitation levels are lowest in August, and the forecasting capability is relatively better in autumn. In terms of seasonal variation, there is a noticeable BIAS in the forecasted precipitation area and amount, with the largest BIAS in winter and the smallest in autumn. Among different forecast lead times, the 24-h forecast performs the best. The distribution of the annual average daily precipitation shows a dry BIAS in the forecast, particularly pronounced in the western and northeastern parts of Chongqing. Analysis of the precipitation processes during the rainy season reveals that the model can effectively capture the different stages of precipitation processes, with the 24-h forecast being the closest to the observed precipitation.

     

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