利用雷达回波三维拼图资料识别雷暴大风统计研究

Statistical study of the identification of thunderstorm gale based on the radar 3D mosaic data

  • 摘要: 应用雷达回波三维组网拼图数据、加密自动站和地面灾害大风资料,对2008—2012年京津冀地区20次区域性雷暴大风天气过程进行了统计。检验了基于模糊逻辑建立的利用回波强度识别大风的算法,分析了大风出现的位置。该大风识别算法确定了雷暴大风的6个雷达识别指标及其对应的权重系数和不同季节的隶属函数。检验分析块状回波、带状回波和片状回波3类大风过程的识别效果,结果表明:块状回波类大风是由孤立的强单体风暴引发的,风暴单体具有回波强、回波顶高、垂直积分液态水含量大和移动快等特点,雷暴大风多出现在风暴单体附近且二者移动路径一致;带状回波的长度远大于宽度,主要包含飑线和弓状回波,大风影响范围广且多位于带状回波的前沿一带;片状回波多指大面积层云回波中镶嵌着强回波单体块的混合回波,对应出现的雷暴大风多位于风暴单体的周边区域。3类回波识别到的可能出现大风区域与实测大风范围基本吻合,块状、带状和片状3种类型的雷暴大风命中率分别为96.2%、68.6%和45.3%,漏报率分别为3.8%、31.4%和54.7%。由于垂直积分液态水含量偏低和回波强度弱,片状雷暴大风识别漏报相对较多;空报原因除了与测站分布稀疏有很大关系外,也与识别算法本身有关。识别检验证明雷暴大风综合识别方法是合理可靠、切实可行的,可以为雷暴大风的短时临近预警业务和系统开发提供技术支撑,这一工作也为进一步预警大风出现的位置提供了基础。

     

    Abstract: Based on the radar mosaic 3D data,automatic weather stations observations and disaster wind data, twenty cases of thunderstorm gale from 2008 to 2012 in the Beijing-Tianjin-Hebei region are statistically analyzed to develop an automated detection of thunderstorm gale with the fuzzy logical based algorithm. The capability of the algorithm is examined. In the method, the six main radar identification indices of ground gale are given with the corresponding membership functions and weight coefficients determined. All the gale is tested and analyzed, including the three types of echo, i.e. the massive echo, banding echo and floccus echo. The results show that the massive echo is triggered by the strong storm monomer with strong echo, higher echo top, bigger vertical integrated liquid water content (VIL) value and faster moving speed, and in this case the gale occurs nearby the thunderstorm cell with the same route as that of the cell; the banding echo mainly contains the squall line and the bow echo with its length greater than the width and the impact range of strong wind located at the forefront of the band echo; the floccus echo generally refers to the mixed echo with large area layer echo embedded by the isolated massive echo, and the strong wind area situated around the storm monomer. The wind range for the three types identified is generally consistent with the real wind, and the hit rate of massive echo, banding echo and floccus echo is respectively 96.2%, 68.6% and 45.3% with the missing rate of respectively 3.8%, 31.4% and 54.7%. Lower omission rate of floccus echos gale is because of weak echo intensity and lower VIL and missing rate is caused by the sparse station distribution and algorithm. This also proved that the automatic identification method is efficiently and feasible, it has important practical guiding significance for an operational system in short-term forecasting and nowcast warning. The work also provides a foundation in warning the position of surface gale.

     

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