摘要
利用NCEP 1 °×1°再分析资料、风云卫星资料以及地面常规气象观测资料,对2015年8月16～18日发生在南充的一次区域性大暴雨进行分析,探讨强降水发生发展的机制.结果表明,此次暴雨过程主要分为2个阶段:第1阶段为低空切变线及前期不稳定能量释放引发强对流天气;第2阶段为西南低涡影响,影响时间较长.此次西南低涡生成属于高原切变类,低涡首先出现在500 hPa切变线南侧下层的850 hPa,后垂直发展到700 hPa,深厚阶段正涡度柱伸展至400 hPa,呈自下而上的近垂直结构.在西南低涡维持下的中尺度对流系统云团是这次暴雨产生的重要系统.南充低层辐合高层辐散,加之低层辐合中心与西南低涡伴随的低空急流耦合发展,有利于上升运动的发展和维持,为暴雨提供了有利的动力作用.南充受西太平洋副高西侧持续的西南低空急流带来孟加拉湾的充沛水汽,且中低层南充一直处在水汽辐合上升区域,有利于水汽的垂直输送.
Abstract
A heavy rainfall in Nanchong City was analyzed from August 16 to August 18,2015 by using NCEP 1° × 1° reanalysis data,FY satellite data and ground conventional meteorological observation data.The mechanism of heavy rainfall was discussed.Research results showed that this heavy rainfall could be divided into two stages:the first stage was severe convection weather caused by previous unstable energy release and low level shear line;the second stage was the influence of southwest vortex in a long period of time.This southwest vortex belonged to the plateau shear.Low vortex firstly generated on the 850 hPa under the south site of 500 hPa shear line.Then,the southwest vortex developed to 700 hPa vertically.The deep stage of positive vorticity stretched to 400 hPa,showing nearly vertical bottom-up structure.The mesoscale cloud cluster maintained by southwest vortex was an important system for this rainfall.There were low level convergence and high level divergence in Nanchong City,coupled with low-level convergence center and the low-level jet of southwest vortex.The dynamic condition was helpful to the development and maintenance of the vertical motion.Low-level convergence in convection and relatively strong upward motion provided favorable dynamics for rainstorm.Abundant water vapor from the Bay of Bengal was brought to Nanchong City by southwest lowlevel jet in the west site of the western pacific subtropical high.The middle and lower atmosphere on Nanchong was in the region of water vapor convergence,which was conducive to the vertical transport of water vapor.
基金项目
南充市气象局重大气象灾害预警与评估协同创新团队研究项目(2016002)
国家科技期刊平台
NSTL
维普
万方数据