西安市灰霾天气时间和区域分布特征及影响因素

THE REGIONAL DISTRIBUTIVE CHARACTERISTICS,THE INFLUENCING FACTORS AND TIME OF THE ASH HAZE WEATHER IN Xi'AN CITY

依据1961—2005年共45年,西安、户县、长安、蓝田、临潼、高陵和周至7个气象台站灰霾观测资料,分析了灰霾天气时间和区域分布特征,并根据1996—2005年近10年西安逐月平均灰霾日数与近10年逐月主要气象要素相关性分析,得出:西安市20世纪70年代是灰霾日出现的高峰时期,并呈逐年减少趋势,灰霾发生的中心区域也在向郊区东南部转移;从影响灰霾天气形成的气象条件来看,气温越低,降水量和风速越小,日照越少,气压越高,越有利于灰霾天气的形成。

According to the observed ash haze data from seven meteorological stations in Xi＇an City, in Huxian, Lantian, Gaoling and Zhouzhi counties, and in Chang＇an and Lintong districts over 45 years from 1961 to 2005, it was analyzed the time and regional distributive characteristics of ash haze weather, and the relevance between the average number of the ash haze days per month and the corresponding main meteorological elements in the recent ten years from 1996 to 2005. The results showed that the number of the ash haze weather days in Xi＇ an city reached the peak in 1970s and then decrease gradually. The central area emerging ash haze weather moves towards the southeastern suburb, and the lower the temperature, the rainfall and the wind speed, the less the sunshine and the higher the barometric pressure, it is more likely to form the ash haze weather.