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汪卫国, 平凡, 周括, 等. 2024. 雷达资料循环同化对“4·30”南通雷暴大风模拟的影响研究[J]. 大气科学, 48(X): 1−15. DOI: 10.3878/j.issn.1006-9895.2302.22108
引用本文: 汪卫国, 平凡, 周括, 等. 2024. 雷达资料循环同化对“4·30”南通雷暴大风模拟的影响研究[J]. 大气科学, 48(X): 1−15. DOI: 10.3878/j.issn.1006-9895.2302.22108
WANG Weiguo, PING Fan, ZHOU Kuo, et al. 2024. Influence of Radar Data Cycling Assimilation on Thunderstorm Gale Simulation in Nantong at “4.30” [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(X): 1−15. DOI: 10.3878/j.issn.1006-9895.2302.22108
Citation: WANG Weiguo, PING Fan, ZHOU Kuo, et al. 2024. Influence of Radar Data Cycling Assimilation on Thunderstorm Gale Simulation in Nantong at “4.30” [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(X): 1−15. DOI: 10.3878/j.issn.1006-9895.2302.22108

雷达资料循环同化对“4·30”南通雷暴大风模拟的影响研究

Influence of Radar Data Cycling Assimilation on Thunderstorm Gale Simulation in Nantong at “4.30”

  • 摘要: 基于多普勒天气雷达资料、ERA5再分析资料与地面自动站观测资料,利用WRF(Weather Research and Forecasting)模式、雷达径向风质控及三维变分同化系统(GSI)循环同化对2021年4月30日江苏南通的一次雷暴大风过程进行数值模拟研究,对比分析不同试验方案模拟的雷达反射率、风场与热动力的时空演变和结构特征。结果表明:逐30 min循环同化的Exp3方案较未同化和非临近循环同化方案模拟效果有较好提升,表明循环同化和增加频次有效改善了初始场;UNRAVEL退模糊算法质控有效消除了速度模糊,退模糊处理雷达资料后循环同化方案(Exp4)对此次雷暴大风的雷达反射率和地面风场模拟结果有显著调整,其相应特征和演变趋势与观测基本一致,表明UNRAVEL退模糊质控后循环同化更好的改善了初始场;从热动力场结果来看,Exp4方案动热力结构改善较明显,上层辐散下层辐合,存在“冷—暖—冷”的热动力结构,伴随着强烈上升运动、北高南低的气压分布和强垂直风切变,有助于下沉气流将中高层的水平动量向近地面底层传递,从而激发此次雷暴大风。

     

    Abstract: Using Doppler weather radar, ERA5 reanalysis, and ground automatic station observation data, numerical simulations of a thunderstorm gale process in Nantong, Jiangsu Province, on April 30, 2021, were performed using the Weather Research and Forecasting model, radar radial wind quality control, and GSI (Gridpoint Statistical Interpolation) cycle assimilation. The spatiotemporal evolution and structural characteristics of radar reflectivity, wind field, and thermal dynamics simulated by various experimental schemes were compared and examined. Results revealed that the cycling assimilation scheme (Exp3) with an assimilation interval of 30 min has substantially enhanced the simulation results compared with the nonassimilated and nonadjacent cycling assimilation schemes, demonstrating that cycling assimilation and increased frequency effectively improve the initial field. The UNRAVEL dealiasing algorithm effectively eliminates the velocity ambiguities and enhances the initial field in the cycling assimilation scheme (Exp4) after radar data processing using dealiasing, resulting in substantial adjustments in the simulated radar reflectivity and surface wind fields for this thunderstorm wind event. The corresponding features and evolving trends align with the observations, indicating that the cycling assimilation scheme with UNRAVEL dealiasing is more effective in improving the initial field. Based on the results of the thermodynamic field, the dynamic and thermal structures of the Exp4 scheme are prominently improved with upper-level divergence and lower-level convergence and a “cold–warm–cold” thermodynamic structure. This structure is accompanied by strong upward motion, high pressure distribution in the north and low pressure distribution in the south, and strong vertical wind shear, which helps transfer the horizontal momentum from the mid-high level to the near-surface layer through the sinking airflow, thereby provoking this thunderstorm gale event.

     

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