2013年常州市灰霾天气特征分析

Analysis of Characteristics on Haze Weather in Changzhou

利用2013年环境空气监测资料和同期的地面气象资料,分析了常州市灰霾天气的时间变化特征,对灰霾天气发生时空气质量和气象要素的变化特征进行了分析。结果表明:2013年常州市灰霾天气频发,12月灰霾天数最多,发生重度灰霾天气的频率最高。不同空气质量级别情况下都可能发生灰霾天气,以轻度污染发生频次最高。灰霾在各时次均可能发生,07:00-09:00出现频率最高,15:00-18:00出现频率最低,灰霾高发的冬季,日变化特征不明显。东北和东北偏东风向下、地面24 h正变温时,霾的发生几率更大,相对湿度在75%~80%时,灰霾发生概率最大,此后随相对湿度减小而降低。灰霾天气下,随着相对湿度的升高,能见度水平呈明显下降趋势,最低仅0.7 km。

The temporal characteristics, the characteristics of air quality and meteorological elements when haze occurs are statistically analyzed based on the ambient air monitoring data and the ground meteorological data during the same period in2013.The results show that haze occurs frequently in Changzhou in 2013, both the highest frequency of the haze and the severely smoggy weather occur in December. Haze can occur at any time under different air quality level with the highest rates of the mildly pollution, and a high incidence of haze mainly occurs at about 07:00-09:00 while a lower incidence of haze mainly occurs at about 15:00-18:00. Although characteristics of diurnal variation is not obvious in winter which is the high risk season of haze. The meteorological elements exhibit variations when haze occurs, especially obvious in wind direc-tion, humidity and 24 hours of pressure difference. Haze is more likely to happen under northeast wind with positive tempera-ture difference of 24 hours and the relative humidity between 75 and 80 percent while the likelihood of haze decreases with the drop of the relative humidity. Under haze weather, As the relative humidity increased, the visibility obviously decreased with a minimum 700 meters when the relative humidity between 90 and 95 percent.