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

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.