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2026年7月6日鄂东超级单体龙卷观测特征分析

Analysis of observational characteristics of supercell tornadoes in eastern Hubei on 6 July 2026

  • 摘要: 2026年7月6日受台风和东北冷涡的共同影响,鄂东地区发生了3个龙卷,其中2个达EF3级、1个为EF1级,造成严重的人员伤亡和财产损失。基于现场灾情调查资料、ERA5再分析数据、区域气象观测站和双偏振多普勒雷达资料,分析了影响鄂东地区咸宁、鄂州的2个EF3级龙卷的天气背景、环境条件和雷达特征。结果表明:龙卷发生在东北—西南走向的台风倒槽附近,具备最不稳定对流有效位能(MUCAPE)>2 000 J·kg−1,整层可降水量(PWAT)>60 mm,0—3 km风暴相对螺旋度(SRH3)>200 m2·s−2、抬升凝结高度(LCL)低和垂直风切变强等有利于超级单体龙卷的环境条件。两个EF3级龙卷由同一超级单体风暴向东北方向移动过程中先后产生,该超级单体具备深厚持久的中气旋和垂直倾斜结构特征,龙卷出现在超级单体钩状回波顶端,龙卷发生时段伴随中气旋尺度缩小、涡旋增强及顶高“升高—下降”等信号。两个龙卷均探测到龙卷涡旋特征(TVS)和龙卷碎片特征(TDS)。龙卷发生时TVS最大切变快速跃升,最大切变所在高度下降。在TVS位置对应相关系数(CC)低值区和低差分反射率(ZDR)区,符合TDS的高反射率因子、低ZDR和异常低CC特征。基于上述结果,TVS最大切变的快速跃升与最大切变高度下降可作为强龙卷短临预警的关键信号,对咸宁龙卷提前约7 min;CC降至0.8以下可作为龙卷接地确认与预警的判据。

     

    Abstract: On 6 July 2026, under the combined influence of a typhoon and a northeast cold vortex, three tornadoes occurred in eastern Hubei, two reaching EF3 and one EF1, causing severe casualties and property damage. Based on field disaster survey data, hourly ERA5 reanalysis data, regional meteorological observing stations and dual-polarization Doppler radar data, this paper analyzes synoptic background, environmental conditions and radar characteristics of the two EF3 tornadoes that affected Xianning and Ezhou in eastern Hubei. The results show that the tornadoes occurred near a northeast–southwest-oriented typhoon inverted trough, in an environment favorable for supercell tornadoes, with MUCAPE>2000 J·kg−1, PWAT>60 mm, SRH3>200 m2·s−2, a low LCL and strong vertical wind shear. The two EF3 tornadoes originated from the same northeastward-moving supercell, which possessed a deep and persistent mesocyclone and a vertically tilted structure; the tornadoes occurred at the top of the hook echo, accompanied by mesocyclone contraction, cyclonic vortex intensification and a rise-then-fall of the mesocyclone top. TVS and TDS were detected for both tornadoes. The maximum TVS shear increased rapidly and the height of the maximum shear decreased when tornadoes occurred. Low CC and low ZDR at the TVS position were found, consistent with the TDS features of high reflectivity factor, low ZDR and abnormally low CC. These results indicate that the rapid increase in maximum TVS shear and the decrease in the height of the maximum shear can serve as a key nowcasting signal for strong tornadoes, providing a lead time of about 7 min for the Xianning tornado; CC dropping below 0.8 can be used as a criterion for tornado touchdown confirmation and warning.

     

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