西安雾日和霾日时空特征分析

摘要

The characters of foggy day,misty day and hazy day were analyzed based on information in 7 meteorological stations in Xi'an during 1960-2012.The results showed that during 1960-2012 in Xi'an,foggy day occurs most in mountainous regions and few in plains; misty day occurs most in cities and few in suburbs;hazy day occurs most in cities,followed by inner and outer suburbs.Annual foggy day in Xi'an changed from increasing to decreasing; misty day was increasing by 9.0 d/10 a; hazy day was decreasing by-7.7 d/10 a.During the 53 y in Xi'an,foggy day was shown in a singly-valley shape,and the minimum appeared in summer and the maximum appeared in winter; misty day was shown in a "V"-shape,and the minimum (7.6 d) appeared in June and the maximum (3.8 d) in December;hazy day was shown in a "U"-shape from May to September and the maximum in January (6.1).%利用1960～2012年西安区域7个气象站的历史地面观测资料,统计分析了西安地区雾日、轻雾日及霾日的时空变化特征.结果表明,1960～2012年西安区域雾日分布呈近山区多、平原区少的特点;轻雾日的分布呈城区多发、郊区少发的特征;霾日在城区为高发区,近郊次之,远郊最少.西安地区年平均雾日数呈现先增加后减少的变化特征,轻雾日数以9.0 d/10 a的速率呈波动性显著增加趋势,霾日以-7.7 d/10 a的速率呈波动性显著减少趋势.西安地区雾日数在年内呈单谷型分布,全年最低值出现在夏季6月(0.2 d),冬季12月出现最高值(3.8 d);轻雾日数在年内呈“V”型分布,全年轻雾日数最低值出现在6月(7.6d),冬季12月份出现最多(17.4 d);霾日数在年内呈“U”型分布,春末(5月)～初秋(9月)霾日出现频率在年内变化曲线上表现为一个宽广的“U”型底部,在冬季1月份上升至最高值(6.1 d).