摘要
利用常规气象资料和NCEP再分析1°×1°资料,从大气环流形势和物理量特征对广西防城港市一次连续性大暴雨过程进行诊断分析,结果表明:1)南亚高压一直位于季风槽上空,季风槽强盛且长时间维持,期间配合有高空槽、低涡触发副高边缘不稳定能量的释放,是造成连续性强降雨的直接原因;2)大暴雨期间南海季风槽强度弱于印度季风槽,正相对涡度带的大值区与槽线流线的位置比较吻合,季风槽槽区在对流层低层具有很明显的辐合特征;3)整个过程地面在越南北部靠近防城港一带存在闭合低压,南北向等压线明显,有利于强降水发生;4)水汽来源主要有孟加拉湾地区和南海地区;5)季风槽影响前后,925 h Pa的垂直螺旋度在越南北部靠近防城港一带有一个明显先增大然后维持最后减弱的过程,这对预报防城港市季风槽暴雨有一定的指示意义。
Based on the conventional meteorological data and 1°×1° NCEP 6 - hourly reanalysis da- ta, the causes of a persistent heavy rainstorm which was caused by a monsoon trough were diagnosed from the atmospheric circulation situation, physics diagnostic field in Fangchanggang, Guangxi. The conclusions are as follows ： （ 1 ） The South Asia high was located over the monsoon trough, which was strong and maintained for a long time, and an upper - level trough and a low vortex triggered the release of energy on the edge of a subtropical high. It directly caused the rare persistent heavy rainstorm; （2） The strength of a South China Sea monsoon trough was weaker than a monsoon trough over India. The position of a large - value area of a positive relative vortieity zone was consistent with that of the stream line of the trough and the monsoon trough region had obvious characteristics of convergence in the lower troposphere. （3） There was a closed cyclone in northern Vietnam and Fangehenggang and a north -south isobar was significant, which was conducive to the occurrence of strong precipitation. （4） There were two main sources of water vapor, one was from the bay of Bengal region and the other was from the South China Sea area. （ 5 ） Before and after the monsoon trough, the vertical helicity on 925 hPa in northern Vietnam and Fangebenggang increased first, and then maintain and finally decreased, w＇hieh is a good indicator for the forecast of heavy rainstorms in Fangeheng- gang which are caused by the monsoon trough.
出处
《广东气象》
2017年第5期6-11,共6页
Guangdong Meteorology
关键词
天气预报
季风槽
连续大暴雨
环流形势
水汽通量
垂直螺旋度
防城港市
weather forecast
monsoon trough
persistent heavy rainstorm
circulation situation
vapor flux
vertical helieity
Fangehenggang city
