Analysis on the characteristics of 4 convective storms with low-echo-centroid of short-term heavy rainfall in Wuhan
Based on hourly and 5-minute observation data of automatic weather station, swan mosaic product of radar combined reflectivity factor in the middle reaches of the Yangtze River and NCEP FNL reanalysis data, the characteristics of four convective storms with low-echo-centroid type of short-term heavy precipitation in Wuhan were analyzed. The results showed that: (1) the characteristics of convective system induced by different weather background were different. Under the background of warm forcing, the environmental conditions were high energy and high humidity, and the accumulation of thunderstorm cold pool was conducted to triggering linear convection in the stable precipitation front; under the baroclinic frontogenesis background, the convergence of cold and warm was intense, and the baroclinic was strengthened; there were more mesoscale cyclone waves on the ground, and the stable precipitation in the front area was often accompanied by a short-term strong drop Under the quasi barotropic background, the baroclinic atmosphere was weak, but the high-energy and high humidity environment as well as the near surface layer flow field forcing and local thermal difference were easy to trigger severe thermal convection activities. (2) According to the radar echo characteristics and precipitation characteristics of convective storms, TS type moved faster, resulting in a small range of short-term heavy rainfall; quasi-stationary type showed that the echo of large-scale stratiform cloud with zonal trend was stable, and there were multiple cumulus convective echoes in the middle. The precipitation enhancement in each stage corresponds to the new convective cell passing through Wuhan station; the consolidation type was in the circulation When the wave merges, it was often accompanied by the occurrence of heavy rainfall, and the echo shape and direction after merging affect the intensity and duration of precipitation. (3) Under different environmental background, trigger inducement and organizational form, the surface meteorological elements before and after the occurrence of short-term heavy rainfall showed different change characteristics; the different front characteristics and convection trigger positions leaded to different temperature changes. (4) Ground mesoscale system played an important role in triggering and organizing the development of MCS. Its generation, elimination and transformation usually heaved a certain advance in time for MCS. Paying attention to the development and evolution of ground mesoscale systems such as ground convergence line and temperature front area was of great significance for predicting the triggering and organizational evolution of MCS.
The Key Program of the Chinese Academy of Sciences