Atmospheric Conditions of Tornado Genesis and Universal Tornadic Index Based on Reanalysis Data

The authors used the NCEP reanalysis system to make integrated analysis by region and have found environmental conditions associated with tornadoes taken from Year-book of Meteorological Disasters in China (Xu Xiaofeng, 2005-2012) for the period of 2004-2009. Then an index has been formulated from analyzing kinds of parameters derived from proximity soundings. Results show that favorite significant tornado environments were concentrated in the east of China. The coordinating between low and high situation was important as well as instability energy accumulation and vapor transport. It was also proven that tornadoes in China occur in conditions accompanied by moderate convective available potential energy (CAPE), high wind shear (0-6 km layer shear and 0-1 km layer shear) and low cloud base. The results of this study were used to create a universal tornadic index based on NCEP reanalysis data and designed to forecast activity in tornadic environment. The quality of this index was tested with tornado activities in China for the period from 2010 to 2011.