1981—2013年上海地区强降水事件特征分析

Characteristics of heavy rainfall events in Shanghai region from 1981 to 2013

利用1981—2013年上海地区11个基本气象站逐小时降水资料,分析上海地区强降水事件的时空分布和雨型特征。结果表明:近33 a来上海地区强降水事件发生频次总体呈线性增加的趋势(2.9站次/10 a),强降水事件的增加主要是由于短持续强降水的增加造成的。上海地区强降水事件为夏季多发,短持续强降水为午后多发。强降水事件发生频次的空间分布反映了明显的城市雨岛特征。静止锋和副热带高压是造成上海地区强降水事件的主要天气型,静止锋型强降水以降水强度偏小的长持续强降水为主,副热带高压型强降水具有降水强度大、历时短的特点;副热带高压型强降水事件发生频次及其增加趋势均为上海中心城区大于郊区。强降水事件的雨型大部分为雨峰在前部的单峰雨型,短持续强降水事件雨峰的集中度和强度比长持续强降水高,此类雨型降水集中,易引起内涝灾害。

Based on hourly precipitation data at 11 weather stations in Shanghai from 1981 to 2013, spatial and tem- poral distributions and patterns of heavy rainfall events （HRE） were investigated. The results show that HRE is in a linear increasing trend with 2.9 times per decade in recent 33 years, and its increasement mainly comes from the contribution of short-term heavy rainfall events （STHRE）. HRE is normally to happen in summer, while STHRE is usually to occur in the afternoon. Spatial distribution of the HRE frequency presents significant urban rainfall island features with the higher value at urban downtown and leeward areas. The main weather types for the HREs include stationary front and subtropical high weather types. The hourly mean precipitation of subtropical high weather type for HREs is the greatest among all weather types and average durarion is the shortest. The frequency of subtropical high weather type for the HRE and its increasing trend both are higher in the urban area than in the rural area. The majority rainfall patterns of HRE are unimodal, and rainfall peak is in front. Concentration degree and intensity of rainfall peak for STHREs is stronger than those of long-term heavy rainfall events （LTHRE）, which usually leads to waterlogging disaster becasuse of concentrated precipitation.