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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-Term Nowcasting Forecast Technology for Short-Time Heavy Precipitation Based on Multi-source Data Fusion Integration

  • 摘要: 采用福建省及周边邻省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、RiRi=0.5°)、Ntop=5(Ri内取降水量排名前5名)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1 h预报时效的TS可达37.5%、32.2%,2 h预报时效可达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=15,1 h预报时效的TS可达16.2%和16.6%、2 h预报时效可达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 for short-time heavy precipitation (greater than 20 mm h−1) for 1–12 h at 1-h intervals in Fujian Province and its neighboring provinces is established based on neighborhood analysis with an optimal TS (threat score). This model utilizes real-time precipitation observational data from automatic weather stations, 0–120 min quantitative precipitation forecast from SWAN-QPF (Severe Weather Automatic Nowcasting) of the China Meteorological Administration, and forecast precipitation data from global and regional models during April–September 2021–2023. A neighborhood test with a radius of 40 km is adopted. The results indicate that the accuracy of the nowcast in the initial hours is greatly improved by incorporating real-time precipitation observations to forecast the short-time heavy precipitation (persistence forecast) compared with forecasts based on multimodel optimal weight integration. After the optimal elimination threshold correction, the TS can reach 37.5% for 2021 and 32.2% in 2022 for 1-h forecast lead time when the forecast precipitation is calculated using 10 min real-time precipitation prior to the forecast production, with a neighborhood radius (Ri) of 0.5° and the average of the top 5 (Ntop=5) heavy precipitation stations within Ri. The TS can reach 22.2% for 2021 and 19.5% in 2022 in 2-h forecast lead time. The TS of the consensus forecast combining global and regional models with optimized weights can reach 16.2% for 2021 and 16.6% in 2022 for 1-h forecast lead time (18.0% and 14.2% in 2-h forecast lead time, respectively) when the forecast precipitation is calculated using Ri=0.6° for each model and Ntop=15. The SWAN-QPF short-time heavy precipitation predictions revised by the optimal elimination threshold (with Ri=0.3° and Ntop=15) are also better than the multimodel optimal weight integration, but they are less effective than predictions using real-time observational precipitation in the first few hours. For the 3–12-h forecast lead time, multimodel optimal weight integration is better than the other two methods. The above mentioned multisource data, revised by the optimal elimination threshold, are further integrated with optimized weights for 1–4-h forecast lead time, whereas multimodel optimal weight integration is adopted in the 5–12-h forecast lead time to establish the short-time heavy precipitation model for 1–12-h forecast lead time at 1-h intervals. The parameters trained with 2021 and 2022 data are applied to forecast short-time heavy precipitation in Fujian in 2023, yielding TS of 42.7%, 28.8%, 23.1%, and 20.2% for the 1–4-h forecast lead time, respectively, with all values exceeding 17% for the 5–12-h forecast lead time.

     

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