Research On Structure Difference And Mechanism Of Three-type Strong Storms In Jianghuai Area

Based on a great deal of real observation data, radar and upper sounding data, the environment fields of strong storms were analyzed, and their structures and differences were studied. Then their warning indices were summarized, and their mechanism were explored. The main conclusions were as followings. (1) The environment field characteristics were refined. The temperature and θ se differences between 850hPa and 500 hPa, vertical wind shear and CAPE of three-type storms had certain thresholds before strong storms occurred. The storm severity index (SSI) were bigger than 100. Big hail storm and gale storm had particular environment fields characteristics. (2) The structure differences and their explanations were done. The regression model of maximum hail diameter were estimated. Some structure parameters of big hail storm were appreciably bigger than gale storm, and their parameters were obviously bigger than tornado storm. The possible reasons of structure differences were discussed. (3) The warning indeces were proposed between environment field and radar monitoring. These indexes had storm top, maximun echo intensity, vertical wind shear, VIL and so on. Big hail storm and gale storm had particular warning indexes. (4) The estimation of acting force and formation mechanism of strong storm were explored. The acting force was estimated by radar monitoring data. The offcenter force had remarkable differences between three-type storms. The flow field of big hail storm had severe upward and downward movement. Ice crystal condensed after lower wet air was transported into middle layer. The violent downward and upward movement prompted ice crystal growth, finally leaded to hail down to the ground. To gale storm, the downward airflow was divided into two airflows at lower layer, then local gale occurred. The supercell tornado storm had downward airflow convergence near the ground, then one tornado was produced nearby mesocyclone or TVS. The non-supercell tornado storm had two types of anti-wind and convergence line.