关键词: 暴雨, 中尺度对流系统, TBB, 雷达回波

Abstract:

Based on the meteorological observation data from weather stations and automatic weather stations, cloud image from MODIS, TBB of FY-2D and FY-2E, reflectivity factor and radial velocity from Doppler weather radar and NCEP/NCAR FNL reanalysis data with 0.5°×0.5° spatial resolution, the characteristics of mesoscale convective system (MCS) during a rare short-time rainstorm in Bayangol Mongol autonomous prefecture of Xinjiang on 4 June 2012 were analyzed. The results are as follows: (1) During the short-time rainstorm, there were two obvious mesoscale convergence lines of wind field, and the moving direction of convergence lines was corresponding to the movement of MCS. (2) The multiple meso-β and meso-γ scale convective cloud clusters gradually merged and strengthened to causing the rainstorm during the moving. Rainstorm mainly occurred in dense isoline zone of TBB, and the formation, development and disappearance of area with TBB≤-52 ℃ was corresponding to the start, duration and end of the rainstorm.(3) The vertical structure of MCS was divergence in upper layer and convergence in low layer, and the rainstorm area occurred in the tail of ‘人’ shape echo, the reflectivity factor of MCS cloud clusters was more than 50 dBZ during the rainfall. The satellite and radar data had better monitoring significance for the formation, movement, development and disappearance of MCS. (4) Before the rainstorm, there was constantly water vapor transport in the south of Bayangol Mongol autonomous prefecture of Xinjiang, the water vapor and energy were continually lifted to the upper layer due to the block of terrain in Tianshan mountains, which was beneficial to the development of MCS, and provided vapour and dynamic condition for the rainstrom.

Key words: rainstorm, mesoscale convective system, TBB, radar echo