摘要
对近30年渤海湾北部葫芦岛站出现大雾天气时的气压场进行模糊聚类分析,采用4个客观指标确定了最优分类数,并对各聚类的气压场分布、各聚类大雾频数逐月变化、大雾发生期间风向风速和能见度日变化进行了研究。结果表明,葫芦岛站点出现大雾时气压场可分为4类:冷锋前部型、高压前部型、高压后部型、鞍型场型,冷锋前部型主要发生在春季和夏季,高压前部型和鞍型场型主要发生在冬季和春季,高压后部型全年均可发生,4类中只有鞍型场类年频数趋势系数通过了95%信度检验。在低压冷锋锋面前部型和高压后部型中风速以西南风为主,而高压前部型中受海陆风效应影响,北风风向百分比多于西南风向,鞍型场中西南风百分比多于北风风向。
The pressure fields for the heavy fog events occurred at Huludao weather station around the Northern Bohai Bay for nearly 30 years are analyzed by using the Fuzzy C-Means（FCM）Clustering Algorithm,and the optimal cluster number is decided based on four scalar validity measures,and then the pressure pattern and monthly frequency for each cluster,wind direction and magnitude,relative humidity,diurnal variation of visibility at the weather station are also studied.The results show that the pressure patterns for heavy fog weather at the Huludao station can be divided into four types：ahead of a cold front,ahead of a high pressure system,rear of a high pressure system,and col pressure field.The pattern ahead of a cold front occurs mainly in spring and summer,while patterns ahead of a high pressure system and col pressure field happen mostly in winter and spring,and that in the rear of a high pressure system can arise all the year,within which the annual frequency of heavy fogs for only col pressure pattern passed the 95% significant test.For patterns ahead of a cold front and rear of a high pressure system,the prevailing wind during a heavy fog is southwesterly,because of the effect of land and sea breeze in the rear of high pressure,the percentage of northerly is higher than that of southerly,but the percentage of southwest wind is higher in the col pressure field.
作者
章晗
Zhang Han(Weather Station of Unit 92493 of PLA, Huludao 125000)
出处
《气象科技》
北大核心
2017年第4期725-728,共4页
Meteorological Science and Technology
关键词
葫芦岛
大雾
模糊聚类方法
地面气压场
风向风速
能见度
Northern Bohai Bay
heavy fog
Fuzzy C-Means（FCM）
surface presure field
wind direction and speed
visibility
