廊坊市短时强降水特征分析

Analysis of Short- time Strong Rainfall Characteristics in Langfang

利用廊坊市2006~2010年自动站逐时降水量资料、necp再分析资料、micaps资料,根据气象学原理分析了廊坊市短时强降水的时空特征和强度变化特点,短时强降水发生时伴随的其他强对流天气、短时强降水发生的主要天气形势、短时强降水与物理量场之间的关系。结果表明:廊坊市短时强降水年发生次数的多年平均值为13d,大部分降水日和降水站次出现在主汛期,高峰期在7月下旬~8月上旬;每天的12时、17时、23时前后是短时强降水的高发时段。一天中平均分钟降水量有两个大的峰值,一个出现在凌晨1~2时,一个出现在午后的13时。影响短时强降水的天气系统有低涡、西来槽、地面倒槽、地面冷锋、副高边缘西风急流、局地强对流天气等;短时强降水一般都伴随雷暴的发生,有时还会出现大风、冰雹、飚线等强对流天气;在短时强降水发生前,螺旋度、水汽通量散度、相对湿度、假相当位温等物理量与短时强降水中心有很好的对应关系;短时强降水出现站次、降水强度均是南部大于北部地区,短时强降水出现的最早时间也是南部较早。

According to hourly precipitation data of automatic stations in Langfang,NECP reanalysis data and MICAPS data,the following items are analyzed using meteorology principle: the spatial and temporal characteristics of the short-time heavy rainfall and intensity changes in Langfang,other strong convective weathers along with Short-time heavy rainfall,the relationship between the short-time heavy rainfall and the physical field. The results show that the average times annually of short-time heavy rainfall in Langfang are 13 days in recent years. And most of precipitation and precipitation stations appear in the main flood season. The peak is from late July to early August,the high frequency of shot-time heavy rainfall occurs around 12: 00,17: 00 and 23: 00. There are two peaks of average precipitation per minute in one day,one is between 1 and 2 o'clock in the morning,and the other is 13 o'clock in the afternoon. The factors of weather systems affecting short-time heavy rainfall include vortex,westerly trough,ground inverted trough,Surface cold front, the edge of the subtropical high westerly jet and cocal severe convective weather and so on. Short-time heavy rainfall often happens along with thunderstorms,and sometimes,strong convective weather such as strong winds,hail,squall line。Before short-time heavy rainfall,there is good correspondence between the center of short-time heavy rainfall and some physical parameters,like helicity,moisture flux divergence,relative humidity and Pseudo-equivalent temperature. There is a larger short-time heavy precipitation station times and precipitation intensity in south area than north,and the earliest time of shot-time heavy rainfall also occurs earlier in south than north.