江淮地区龙卷超级单体风暴及其环境参数分析

Analysis of the tornado supercell storm and its environmental parameters in the Yangtze-Huaihe region

  • 摘要: 利用多普勒雷达探测资料和NCEP再分析资料,对2003—2010年发生在江淮地区的6个龙卷超级单体风暴及其环境参数进行了分析。研究表明:(1)龙卷超级单体风暴HBASE平均为1.7 km,HTOP平均为9.1 km;H多在风暴的下部,近于下部的1/4处。HBASE平均值比江淮地区各种超级单体的平均值低得多,HTOP则略低。(2)龙卷超级单体IVIL平均为25.6 kg/m2,ZMX平均为54.8 dBz。和江淮地区超级单体相比,龙卷IVIL要小得多,而龙卷ZMX略低。(3)龙卷超级单体的中气旋MBASE、MTOP和MSHR平均值分别为1.2 km、3.9 km和14.4×10-3s-1,和江淮地区超级单体相比,龙卷MBASE、MTOP明显低,而MSHR略高。(4)TVS参数最强时的VAD在12—45 m/s,VLLD多大于30 m/s,VMXD多超过30 m/s,VMXD的高度不低于0.8 km,TDPT在2.4—6.4 km,TBASE在0.7—1.5 km,TTOP在2.3—6.4 km,TMXSHR超过22×10-3s-1。TVS参数最强时间与龙卷实际时间基本吻合,平均相差4.2 min;平均而言,TVS出现后6 min有龙卷发生。(5)雷达推算的龙卷超级单体的0—6 km风垂直切变比江淮地区超级单体的风垂直切变平均值高15.2%;龙卷发生前ICAPE平均为1752 J/kg,IK为38℃,850 hPa到地面风切变平均超过12 m/s,850—500 hPa温差平均为23.7℃。龙卷发生前能量处在中等到强的状态,大气不稳定性较强,风垂直切变大。

     

    Abstract: Based on the Doppler radar detection data and the NCEP reanalysis data, 6 tornado supercell storms in the Yangtze-Huaihe region from 2003 to 2010 and their environmental parameters were analyzed. The results show that: (1) HBASE average of the tornado supercell storms was 1.7 km, HTOP average was 9.1 km. The height of maximum reflectance factor was mostly in the lower part of the storm, close to somewhere quarter to its base. HBASE average was much lower than the mean averaged over all the supercell storms of the Yangtze-Huaihe region, but HTOP average was slightly lower. (2) IVIL average was 25.6 kg/m2, and ZMX average was 54.8 dBz. IVIL average was much smaller than the mean averaged over all supercell storms of the Yangtze-Huaihe region, but ZMX average was slightly lower. (3) MBASE average of the tornado supercell storms was 1.2 km, MTOP average was 3.9 km, and MSHR average was 14.4×10-3s-1. Compared to the average for the Yangtze-Huaihe region, tornado MBASE and MTOP were obviously lower, but MSHR was slightly lower. (4) When TVS (Tornado Vortex Signature) parameters got the maximum value, VAD was between 12 and 45 m/s, the VLLD was greater than 30 m/s, VMXD was larger than 30 m/s, the hight of VMXD was not lower than 0.8 km, TDPT was between 2.4 and 6.4 km, the TBASE was between 0.7 and 1.5 km, TTOP was between 2.3 and 6.4 km, and TMXSHR exceeded 22×10-3s-1. The maximum parameter occurrence time of TVS agreed with the actual time. On average, tornado appeared within 6 min after TVS appeared. And, (5) 0-6 km vertical wind shear of the tornado supercell storm as detected by the radar was 15.2 percent higher than the averaged value over the Yangtze-Huaihe region. ICAPE average was 1752 J/kg, K index was 38℃, wind shear average from 850 hPa to the ground exceeded 12 m/s, and, the temperature difference from 850 to 500 hPa was 23.7℃ before tornado happened. The energy was on a moderate to strong condition, the instability of the atmosphere was higher, and vertical wind shear became larger.

     

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