Characteristics and formation mechanism of a winter haze-fog episode in Tianjin, China
Characteristics and formation mechanism of a winter haze-fog episode in Tianjin, China
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天津冬季灰霾天气特征及形成机制
DOI：
10.1016/j.atmosenv.2014.08.078
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发表时间：
2014-12-01
影响因子：
5
通讯作者：
Zhang, Min
中科院分区：
文献类型：
--
作者：
Han, Su-qin;Wu, Jian-hui;Zhang, Min
2013年1月，我国北方地区出现了多次严重的雾霾天气。对1月10 ~ 12日发生的一次强霾天气过程的特征和形成机制进行了分析。1月12日录得的最低小时能见度为112米。颗粒物和气体污染物的浓度不断增加，在此HF期间。PM2.5浓度的增加速度比SO2和NOx的，和积累的速度是在HF过程的开始比在其他时间更大。HF天的PM2.5、PM10、NOR和SO2的平均浓度分别是非雾霾天的3.9、3.6、2.5和2.1倍。HF天的散射和吸收系数σ（sp）和σ（ap）分别是非HF天的值的4.0和43倍。最高黑碳（BC）浓度比非HF天高约10倍。总碳（TC）、有机碳（OC）和元素碳（EC）浓度均呈上升趋势，且CC的上升速度快于EC。PM2.5中的二次无机污染物（SO 42-，NO3-）也有所增加。HF日的SO 42-和NO3-浓度分别是非HF日的4倍和2倍。HF日相对湿度的增加有利于HF期间硫酸盐和硝酸盐的形成。不利的气象条件是这次HF事件的外部原因。在HF事件开始时，西南风将污染物从研究区域的南部地区输送到研究区域。HF形成后，位于高层的强下降气团严重限制了污染物在垂直方向上的扩散。逆温较强，水平风较弱，限制了污染物的水平和垂直扩散。前期污染物的高层输送和后期污染物的积累以及气溶胶的二次生成是造成这次HF事件的重要机制。(C)2014爱思唯尔有限公司版权所有。
Several heavy haze and fog episodes occurred in northern China in January of 2013. Data were collected and used to analyze the characteristics and mechanisms of formation of the haze-fog (HF) episode that occurred from January 10 to 12. The minimum hourly visibility was 112 m, as recorded on 12 January. The concentrations of particulate and gaseous pollutants increased continuously during this HF period. The concentration of PM2.5 increased faster than that of SO2 and NOx, and the rate of accumulation was greater at the beginning of the HF process than at other times. The average concentration of PM2.5, PM10, NOR, and SO2 on the HF days was 3.9, 3.6, 2.5, and 2.1 times higher than the values in the non-haze days. The scattering and absorption coefficients sigma(sp) and sigma(ap) on the HF days were 4.0 and 43 times higher than the values in the non-HF days. The highest black carbon (BC) concentration was about 10 times higher than on the non-HF days. The concentrations of total carbon (TC), organic carbon (0C), and elemental carbon (EC) all increased, and the speed of the increase in CC was quicker than that of the EC. An increase in secondary inorganic pollutants (SO42-, NO3-) in PM2.5 was also observed. The concentrations of SO42- and NO3- on the HF days were 4 and 2 times those of the non-HF days. The increase in relative humidity on the HF days favored the formation of sulfate and nitrate during HF episode. Unfavorable meteorological conditions were the external cause of this HF episode. The southwest wind transported the pollutants from areas to the south of the study regions at the beginning of the HF episode. After the HF took shape, a strong descending air mass located in the high layer severely limited pollutant diffusion in the vertical direction. The strong temperature inversion and the weak horizontal wind limited the horizontal and vertical dispersion of pollutants. The high layer transport of the pollutants during the early period and the late accumulation of pollutants and the secondary formation of aerosols were important mechanisms for causing the formation of this HF episode. (C) 2014 Elsevier Ltd. All rights reserved.