近50 a鄂西山区雾和轻雾发生频次的非对称变化特征

以湖北西部山区宣恩站为例,利用1959-2009年的地面气象观测资料,对鄂西山区雾和轻雾的气候特征进行分析.结果表明,宣恩年雾日数平均为29 d,总体上呈减少趋势.该地区雾在每个月都有发生,冬季发生频率最高,夏季发生频率最低;该地区年轻雾日数总体上与年雾日数变化趋势相反,呈上升趋势,各月月平均轻雾日数在9~15 d之间,12月平均轻雾日最多,5月平均轻雾日最少.通过分析宣恩51 a来各气象要素的特征发现,夜晚最低气温呈上升趋势,相对湿度和降水变化不明显,14时能见度≥20 km的年日数呈下降趋势.分析认为,雾和轻雾发生频次的非对称变化趋势可能与大气中气溶胶粒子增多有关.

Unsymmetrical variation characteristics of fog and mist frequency in mountain area of west Hubei province in recent 50 years

Climatic characteristics of mountain fog and mist in Xuan''en,west Hubei province are analyzed based on the meteorological data collected from observational station in the period 1959-2009.It is shown that the average fog day is 29 annually and the annual fog days present a decreasing variation trend.The fog events occur in every month with the maximum frequency in winter,the next in autumn and the minimum in summer.It is also found that the annual mist days are generally increasing but there is an opposite tendency with annual fog days.The monthly average mist days in each month are between 9 and 15 with the maximum in December and the minimum in May.Furthermore,studies of the characteristics of meteorological elements point out that the annually average minimum air temperature is rising,the annual average relative humidity at 08:00 and the annual rainfall vary unobviously and the annual days of visibility at 14:00 greater than 20 km are decreasing.Results reveal that the unsymmetrical variation characteristics of fog and mist occurrence frequency probably have the correlation with the increasing aerosol in atmosphere.