重庆永川大风分布特征分析

Distribution Characteristics of Strong Winds in Yongchuan District of Chongqing City

利用2010—2017年常规气象观测资料,分析了重庆永川大风时空分布规律、极端性特征及其天气学背景,为大风预报提供参考。结果表明:(1)永川出现了58次大风过程,风向以NNW或N为主,集中在中部地区和河谷地带。(2)四季皆有大风出现,4月、5月、8月大风较为频繁,主要出现在凌晨前后、傍晚前后。(3)非单站型较单站型大风偏多近40%,非单站型在午后到夜间易发生,影响全区大部地区;单站型02—07时最多,集中在永川中部偏北一带。(4)每年均有9级以上大风出现,区域性最强大风过程为2013年4月5日(A过程),城区最强大风过程为2015年5月10日(B过程),均具有持续时间长、范围广、强度大的特征。(5)对比A、B过程,相同点在于高空有深厚低槽东移过境重庆,地面有冷高压发展,永川受较强冷空气的影响;不同的是,A过程是受冷高压前沿气压梯度差造成的梯度大风,B过程在高空为槽前西南气流,地面上有热低压发展,出现了混合性大风。

In order to provides reference for gale forecast,based on the conventional meteorological observation data from 2010 to 2017,this paper analyzes the spatial and temporal distribution,extreme characteristics and synoptic background of strong winds in Yongchuan District of Chongqing City.The results show that:(1)There are 58 Gale processes in Yongchuan,the wind direction is mainly NNW or N,concentrated in the central region and the river val⁃ley of Yongchuan.(2)There are strong winds in all seasons,and the more frequent in April,May and August,mainly around the morning and evening.(3)The strong wind frequency of non-single station type is 40%more than that of single station type,and the non-single station type is easy to occur from afternoon to night,affecting most areas of the region;the single station type is the most frequent from 02:00 to 07:00,concentrated in the north of Central Yongch⁃uan.(4)The gales above 9 grade happen every year,the strongest regional gale process is April 5,2013(Process A),and the strongest gale process of Yongchuan meteorological station is May 10,2015(Process B),which all have the characteristics of long duration,wide range and strong intensity.(5)Compared with A and B processes,the same point is that there is a deep trough moving eastward through Chongqing,with the development of cold high pressure on the ground,and Yongchuan is affected by strong cold air;the difference is that process A is a gradient gale caused by the pressure gradient difference in the front of the cold high pressure,while the process B is a mixed gale caused by the development of the thermal low pressure on the ground and southwest airflow in front of the high trough.