2022年桂林“龙舟水”降水特征及形成机制分析

Precipitation characteristics and formation mechanism of the dragon-boat precipitation in Guilin in 2022

利用常规气象观测资料、欧洲再分析资料对2022年桂林“龙舟水”的降水特征和成因进行分析。结果表明,桂林“龙舟水”降水由三次连续性暴雨、局地大暴雨到特大暴雨过程组成,雨量中心主要在铁路沿线湘桂走廊一带,累计雨量具有极端性,三次暴雨过程具有相同的低层水汽输送特征,异常强盛的西南季风带来孟加拉湾和南海的水汽输送到桂林,影响系统有中层低涡稳定控制、高空槽的东移,低层有低空急流、静止锋等。暴雨触发与低空急流加强、切变线、低涡系统的控制,以及副热带高压加强有关,湘桂走廊地形强迫也是暴雨的成因。低空急流的加强与高空槽、低涡迫近导致气压梯度加大有关。

Based on conventional observation data and ERA5 reanalysis data,the precipitation characteristics and causes of the dragon-boat precipitation in Guilin in 2022 were analyzed.The dragon-boat precipitation in Guilin consists of three continuous rainstorms,local heavy rainstorms and extreme rainstorms.The rainfall center is mainly in the Xianggui Corridor along the railway,and the accumulated rainfall is extremely high.The three rainstorms have the same characteristics of low-level water vapor transport.The unusually strong southwest monsoon brings water vapor from the Bay of Bengal and the South China Sea to Guilin,and the influencing systems include the stability control of the middle vortex,the eastward movement of the upper trough,and the low-level jet and the stationary front.The triggers of the rainstorms are related to the strengthening of low-level jet,the control of the shear line,vortex system and the strengthening of subtropical high,and the topographic forcing of the Xiang-Gui corridor is also the cause of rainstorm.The intensification of the low-level jet is related to the increase of the pressure gradient caused by the approaching of the high trough and low vortex.