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基于多源资料融合集成的短时强降水短时临近预报技术

Short-time Heavy Precipitation Short-term nowcasting Forecast Technology Based on Multi-source data Fusion Integration

  • 摘要: 采用福建及周边邻省2021~2023年4~9月自动站降水观测数据、中国气象局强对流天气短时临近预报系统的0~120 min定量降水预报(SWAN-QPF)、全球和区域模式的降水预报数据作为预报因子,以中国气象局对20 mm h-1阈值短时强降水的邻域检验(检验半径为40 km)为检验标准,基于TS(Threat Score)评分最优化原则,优选各预报因子的最优邻域半径(Ri),建立基于邻域的1~12 h逐时短时强降水预报模型。结果表明:自动站降水观测数据采用预报制作时间前10 min(最优时段)累计降水量、Ri=0.5°、Ri内取降水量排名前5名(Ntop=5)站(格)点的平均降水量作为预报降水量进行持续性预报,经最优消空阈值订正后2021和2022年第1 h的TS可达37.5%、32.2%,第2 h可达22.2%、19.5%,相比多模式最优权重集成预报(各模式最优Ri=0.6°、Ntop=15,第1 h的TS可达16.2%和16.6%、第2 h可达18.0%和14.2%),极大提升了临近1~2 h的预报准确率。SWAN-QPF经最优消空阈值订正后的预报(Ri=0.3°,Ntop=15)在1~2 h内的TS也优于多模式最优权重集成预报,但劣于持续性预报。 3~12 h多模式最优权重集成预报的TS评分明显高于另两类预报。在1~4 h内以最优权重进一步集成三类数据,5~12 h采用多模式最优权重集成预报,建立1~12 h逐时短时强降水预报模型。将采用2021和2022年数据训练所得参数应用于福建2023年短时强降水预报,其TS评分在1~4 h分别为42.7%、28.8%、23.1%和20.2%,5~12 h均在17%以上。

     

    Abstract: A forecast model of short-time heavy precipitation (greater than 20 mm h-1) for 1–12 h at 1 h intervals in Fujian is established based neighborhood with optimal Threat Score by real-time precipitation observation data from ground weather stations, 0–120 min Quantitative Precipitation Forecast from Sever Weather Automatic Nowcasting (SWAN-QPF) of China Meteorological Administration, and forecast precipitation data from global and regional models from April to September during 2021–2023. Neighborhood test is adopted, and the test radius is 40 km. The results show that the accuracy of nowcast in the couple of hours is greatly improved by using real-time precipitation observation to forecast the short-time heavy precipitation (Persistence forecast) compared with using multi-model optimal weight integration. After the optimal elimination threshold correction, the TS in the future first hour can reach 37.5% for 2021 and 32.2% for 2022 when the forecast precipitation is calculated with 10-min real-time precipitation before the forecast production, the neighborhood radius (Ri) of 0.5°, and the average of the top 5 heavy precipitation stations (Ntop=5) in Ri. And at the second hour, the TS can reach 22.2% for 2021 and 19.5% for 2022. The TS of the consensus forecast combining global and regional models with optimized weights can reach 16.2% for 2021 and 16.6% for 2022 at the first hour (18.0% and 14.2% at the second hour) when the forecast precipitation is calculated with the Ri of 0.6° for each model and Ntop=15. The SWAN-QPF short-time heavy precipitation prediction revised by the optimal elimination threshold (the Ri of 0.3° and Ntop=15) is also better than multi-model optimal weight integration, but less than using real-time observational precipitation in the first couple of hours. For the 3–12 h forecast, multi-model optimal weight integration is better than the other two. The above-mentioned multi-source data revised by the optimal elimination threshold are further integrated with optimized weights in the future 1–4 h, and multi-model optimal weight integration is adopted in the future 5–12 h to establish the forecast model of short-time heavy precipitation for 1–12 h at 1 h intervals. The parameters trained with 2021 and 2022 data are applied to forecast short-time heavy rainfall in Fujian in 2023, and the TS are 42.7%, 28.8%, 23.1% and 20.2% in the future 1–4 h, and all above 17% in the future 5–12 h.

     

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