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      基于雷达产品的陆水流域致洪暴雨监测预报

      Flood-inducing rainstorm monitoring and forecasting in Lushui River Basin using radar products

      • 摘要: 陆水流域具有汇流时间短、洪水突发性强等特点,高时空分辨率的雷达资料对该流域暴雨监测预报至关重要。以2024年7月1日陆水流域致洪暴雨为例,在定量降雨预报中使用反射率因子(CR)、强回波厚度(CAPPI)、垂直液态水含量(VIL)等雷达强度产品,在雨团发展判别中使用径向速度(Vc)、垂直风廓线(VWP)等雷达速度产品,以及应用雷达降水估算产品(OHP/THP)展开研究。结果表明:①此次暴雨过程是在高空槽、低涡切变和低层急流的共同作用下产生的,该天气系统的长时间维持为暴雨提供了有利的水汽输送和动力抬升条件;②雷达回波特征包括40 dBZ以上的带状强回波、高垂直液态水含量(VIL值超过10 kg/m2)、3 km强回波厚度(CAPPI在40 dBZ以上)以及显著的列车效应等,是预报大范围短时强降水的关键因素;③径向速度图上的零速度线呈现“S”形和反“S”形特征,指示冷暖平流的交替,逆风区的位置和走向则反映了未来强降水的落区变化,而通过风廓线产品(VWP)分析风场垂直特征可预报降水的时间和强度;④尽管雷达1 h/3 h累积降水产品(OHP/THP)较实况降水量有所低估,但OHP产品在降水范围和中心估算上表现良好,经过偏差订正后,可对暴雨监测预报提供有效参考。

         

        Abstract: Lushui River Basin is characterized by short flow concentration time and high suddenness of floods, making high spatio-temporal resolution radar data crucial for rainstorm monitoring and forecasting in this basin. Taking the flood-inducing rainstorm in the Lushui River Basin on July 1, 2024 as an example, this study utilized radar intensity products such as combined reflectivity (CR), constant altitude plan position indicator (CAPPI), and vertically integrated liquid (VIL) for quantitative precipitation forecasting, radar velocity products including radial velocity (Vc) and vertical wind profile (VWP) for identifying rain cluster development, and operational hydrologic product/thunderstorm hydrologic product (OHP/THP). The results show that: ① This rainstorm process was generated by the combined effects of an upper-level trough, a low-vortex shear, and a low-level jet stream. The prolonged maintenance of this weather system provided favorable conditions for moisture transport and dynamic lifting. ② Radar echo characteristics, including banded strong echoes above 40 dBZ, high vertical integrated liquid content (VIL value exceeding 10 kg/m2), a 3 km thickness of strong echo (CAPPI above 40 dBZ), and significant train effects are key factors for forecasting widespread short-duration heavy precipitation. ③ The zero-velocity line on the radial velocity map exhibits "S" and inverted "S" shaped features, indicating the alternation of cold and warm advection. The location and orientation of the counter-wind zone reflect changes in the future heavy precipitation area. Analyzing the vertical characteristics of the wind field using the wind profiler product (VWP) can help to predict the timing and intensity of precipitation. ④ Although the radar 1 hour/3 hours accumulated precipitation products (OHP/THP) underestimated the actual rainfall amount, the OHP product performed well in estimating the precipitation range and center. After correction, the product can provide an effective reference for rainstorm monitoring and forecasting.

         

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