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文章摘要
引用本文:董全,代刊,陶亦为,周军.2017.基于ECMWF集合预报的极端天气预报产品应用和检验.气象,43(9):1095-1109.
基于ECMWF集合预报的极端天气预报产品应用和检验
Application and Verification of Extreme Weather Forecast Products of ECMWF Ensemble Prediction System
投稿时间:2016-06-21  最后修改时间:2017-05-31
DOI:10.7519/j.issn.1000-0526.2017.09.007
中文关键词: 集合预报, 极端天气, 极端天气预报指数(EFI), SOT(“shift of tail” index)
英文关键词: ensemble prediction system, extreme weather, EFI (extreme forecast index), SOT (“shift of tail” index)
基金项目:公益性行业(气象)科研专项(GYHY201306002、GYHY201206005)和国家科技支撑计划(2015BAC03B03)共同资助
作者单位
董全 国家气象中心北京 100081 
代刊 国家气象中心北京 100081 
陶亦为 国家气象中心北京 100081 
周军 国家气象中心北京 100081 
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中文摘要:
      通过个例总结和大样本分析的方法,本文分析和总结了ECMWF集合预报系统(EPS)中的极端温度和降水预报产品。以上产品主要为08—08时的平均气温、最高气温、最低气温和降水量四个要素的极端天气预报指数(extreme forecast index,EFI)和SOT(“shift of tail” index)。研究显示,气温EFI 和SOT预报效果接近,降水SOT优于EFI。运用过去3年的资料,以TS评分最大为标准,分别确定了不同时效、不同百分位的极端高低温和极端强降水事件在我国的预报阈值,及其对应的各检验参数。对于1%(99%)百分位的极端低温(高温)事件,平均气温EFI和SOT的阈值分别在-0.85(0.75)和0.38(0),最高和最低气温的阈值与平均气温的阈值接近。对于95%和99%的极端强降水事件,EFI的阈值分别在0.45和0.7左右,SOT的阈值分别在-0.6和0.4左右。整体上呈现时效越长阈值越小,预报效果越差;事件越极端,阈值越大的特点。且此时的bias接近或略大于1,表明预报的发生频率与实况比较接近,具有较好的应用价值。气温EFI和SOT的预报效果和阈值存在明显的季节差异,夏季预报较好,阈值较大,冬季预报较差,阈值较小。降水的季节差异不明显。EFI和SOT的预报效果和阈值在空间分布上也存在一定的差异,且不同的产品空间分布差异不同。
英文摘要:
      The extreme weather forecast products of ECMWF ensemble prediction system (EPS) are analyzed and verified. The products include extreme forecast index (EFI) and “shift of tail” index (SOT) of 08-08 BT mean temperature, maximum temperature, minimum temperature and total precipitation. The results indicate that the forecast skill of temperature EFI is similar to SOT for extreme temperature, but the precipitation SOT is better than EFI for extreme precipitation. Using the last 3 years’ dataset, the thresholds and corresponding measures are estimated for different lead times and extreme events over different percentiles of extreme temperature and precipitation, under the criteria of TS maximization. For the extreme low (high) temperature over 1% (99%) percentile, the thresholds of mean temperature EFI and SOT are about -0.85 (0.75) and 0.38 (0.00), respectively. The thresholds of maximum and minimum temperature EFI and SOT are nearly to that of mean temperature. For the extreme precipitation over 95% and 99% percentiles, the thresholds of EFI are about 0.45 and 0.7, and that of SOT are about -0.6 and 0.4. The longer the lead times, the smaller the thresholds and the lower the forecast skills. And the more extreme the events, the larger the thresholds. Under the criteria of TS maximization, the forecast biases are nearly 1, so these thresholds could be applied in the operation. The thresholds and forecast skill of temperature EFI and SOT show significant seasonal variation, with higher skill and thresholds in the summer half year and lower in the winter half year. The temporal variation of precipitation EFI and SOT is not significant. There are spatial variations of these thresholds and forecast skills and they are different for different indexes.
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