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doi:  10.12013/qxyjzyj2016-024
江西省北部地区汛期一次短时强降水过程成因

Characteristics and Causes Analysis of a Short-term Rainstorm Process in Northern Jiangxi
摘要点击 439  全文点击 277  投稿时间:2016-07-25  修订日期:2016-08-26
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基金:  2015年江西省气象局重点项目“强对流天气的格点化预报方法研究”;2014年度江西省地方气象标准制订计划项目“江西省短历时强降水等级标准”.
中文关键词:  暴雨,MCS,低空急流,TBB,列车效应
英文关键词:  rainstorm  MCS  low level jet  TBB  train effect
     
作者中文名作者英文名单位
张弛Zhang Chi江西省气象台, 江西 南昌 330096
蒋璐君Jiang Lujun江西省气象科学研究所, 江西 南昌 330096
引用:张弛,蒋璐君.2016,江西省北部地区汛期一次短时强降水过程成因[J].气象与减灾研究,39(3):170-178
中文摘要:
      利用NCEP 1×1°再分析资料,结合地面高空观测资料、FY 2D卫星TBB资料和雷达探测资料,对2015年6月2日21时—3日09时发生在江西省北部地区的暴雨天气过程进行了分析。结果表明: 1) 500 hPa高空槽和低层切变线直接导致了此次降水天气过程,低空急流带来的充沛水汽和不稳定能量与冷锋的抬升作用加剧了降水的强度,降水发生期间的高空槽和西太平洋副热带高压的少动有利于雨带的维持。2) 在江西省西北部初生的β MCS东移过程中逐渐发展成熟,多个成熟并具有高降水效率的β-MCS依次并持续影响江西省北部地区。假相当位温的垂直分布和低空急流的相互配合,导致江西省北部地区具有极强的不稳定层结和较大的能量输送。垂直上升速度对积云发展的作用证明了降水是由积云处于成熟阶段时产生的,与TBB的分析结果相互印证。3) 此次暴雨天气过程从单纯的对流降水逐步过渡到混合云降水,混合云中低层急流核始终处于江西省东北部地区,混合云中对流作用较强单体的依次经过是导致该地区持续出现降水强度大于20 mm/h、12 h降水量大于200 mm的重要原因。东西向冷锋触发的对流、东西向的低层切变和偏西风的中高层引导气流导致了此次过程的雨带自西向东移动,表现出明显的“列车效应”。
Abstract:
      A rainstorm process, occurred in northern Jiangxi from 21:00 BST June 2 to 09:00 BST June 3 2015, was analyzed by using NCEP 1×1° reanalysis data, surface observation data, TBB (Black Body Temperature) grid data from FY 2D satellite and Nanchang radar products. Conclusions are as follows: 1) The triggers of the rainstorm process were 500 hPa trough and low level shear line. Abundant moisture, strong thermal instable energy brought by low level jet and cold front uplift exacerbated the intensity of the heavy rainfall. During the process, the position of western pacific subtropical high and the upper trough stayed stably which were contributed to the precipitation band remaining in northern Jiangxi. 2) Northern Jiangxi was affected by cold cloud continuously. Newborn β-MCSs (β-Mesoscale Convective System) at west and middle of northern Jiangxi became mature gradually when they moved eastwards, meanwhile, mature β-MCSs with high precipitation efficiency reached successively. due to the vertical distribution of potential pseudo equivalent temperature and low level jet, extreme unstable layer and energy transport existed in northern Jiangxi. Vertical ascending velocity enhanced the development of cumulus, which proved that the heavy precipitation happened in northeast Jiangxi in the mature stage of cumulus, and also was confirmed with the conclusion of TBB. 3) During this process, strong convective precipitation gradually transited to mixing cloud precipitation with the jet stream core always existing in northeastern Jiangxi, and strong convective echoes in mixing cloud passing through the northeast of Jiangxi successively were the reasons of 20 mm/h precipitation intensity and more than 200 mm accumulation precipitation in 12 h appeared in northeastern Jiangxi by analyzing radar products. Combining radar radial velocity with observations, convection aroused by east west direction cold front, east west direction low level shear and west steering flow at high level caused rainband moving from west to east, and formatting the “train effect”.
主办单位:江西省气象学会 单位地址:南昌市高新开发区艾溪湖二路323号
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