摘要
在6个高速公路沿线的新建交通站夏半年资料中挑出13个低能见度天气过程,过程都发生在春末、秋初,降温降雨天气背景下;都是局地甚至单点的,集中在贵都高速地势相对较高处,是锋面雾、地形雾和低云接地成雾与地形影响相互结合的结果。将低能见度过程分为长过程和短过程:长过程有"象鼻"和缓慢下降的前期形态。过程期间能见度震荡幅度大,变化快,反复时间长,影响大。短过程即"山区团雾"占多数,能见度呈"突降"形态,其范围小,强度大,发生突然,影响时间有限,但很难提前预判。从各要素变化特征来看:低能见度过程前湿度往往已达100%,较一般的雾要求更高;温度变化平稳;长过程期间多有弱降水;风速与能见度有负相关,短过程中更明显,反映"山区团雾"与低云有直接关系,一定的风速是其发生的必要条件。山区低能见度过程形成复杂,相邻站点临近时段的两个低能见度过程表现出不同的特性,分别为锋面雾和低云接地成雾。交通站监测和气象资料背景场分析结合,才能提高山区低能见度的监测预报效果。
From 6 new automatic weather stations＇ data in the summer half-year, we selected 13 low visibility events. The results are shown as follows. All the events happened in late spring and early autumn, with weather backgrounds of rainfall and temperature decline. All events took place in limited areas and mainly at two relatively high-altitude stations, because of interactions between terrain fog, frontal fog, low cloud, and topographic influence. The events are classified into long events and short events. Long events showed a trunk-shaped pattern, in which the visibility slowly declined at the initial time. During the events, visibility fluctuated quickly and obviously, and repeated for several hours, posing much larger danger. More events, forming over mountainous areas, were short and the visibility dropped quickly. They were small-sized, strong, and sudden, which had limited influence but was hard to predict. Studies of meteorological elements showed that humidity reached 100% prior to the event and temperature was steady, and most long events had little rainfall and wind speed was negatively correlated with visibility, especially in short events. The ＂mountainous area agglomerated fog＂ connected with low cloud directly and happened with considerable wind speed. Two events that happened over two nearby stations in consecutive points of time were either frontal fog or low-cloud, reflecting the complexity of this type of fog in mountainous areas. Low visibility events in mountainous areas can be better identified by combined use of automatic weather stations and background data of weather condition.
出处
《热带气象学报》
CSCD
北大核心
2015年第2期280-288,共9页
Journal of Tropical Meteorology
基金
公益性行业(气象)专项(GYHY201406029
GYHY201306043)
贵州省科技厅项目(黔科合J字[2013]2148号)
中国气象局预报员专项项目(CMAYBY2013-061)共同资助
关键词
低能见度
监测
交通站
山区
团雾
low visibility
monitoring
automatic weather station
mountain area
agglomerated fog
