洛阳市一次连阴雨天气过程成因分析

Analysis of Causes of a Continuous Rainy Weather Process in Luoyang City

本文利用常规气象观测资料、fnl1°×1°6 h再分析资料和自动雨量站资料等,对洛阳市2017年9月24日至10月17日的连阴雨天气过程的大尺度环流形势特征、影响天气系统及物理量场特征进行诊断分析。结果表明,南亚高压的偏东、200 hPa高空急流的出现并维持、副高的西伸北跳、西风带短波系统活跃、冷空气持续补充南下是这次连阴雨天气的主要原因;连阴雨期间,大气低层湿度大,但水汽辐合和垂直运动条件较弱,致使降水持续时间长但雨量不大;阴雨天气期间,近地层基本维持偏东风或东北风,降水中断间歇,近地面基本为偏南风。

The conventional meteorological observation data,fnl1°×1°6 h reanalysis data,and automatic rainfall sta⁃tion data were used in this paper to diagnose and analyze the characteristics of large-scale circulation situation,influ⁃encing weather system and physical quantity field of the continuous rainy weather process in Luoyang from Septem⁃ber 24 to October 17,2017.The results show that the eastward of the South Asian High,the emergence and mainte⁃nance of 200 hPa upper-level jets,the westward extension of the subtropical high and the northward jump,the active shortwave system in the westerly zone,and the continuous supply of cold air to the south are the main reasons for the continuous rainy weather;during continuous rainy periods,the lower atmosphere has high humidity,but the condi⁃tions of water vapor convergence and vertical movement are weak,resulting in long rainfall duration but not much rainfall;During the rainy weather,the near-surface layer basically maintains easterly or northeasterly wind,the pre⁃cipitation is interrupted intermittently,and the near-surface is basically southerly.