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气象:2020,46(7):948-958
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成都一次重污染过程的气溶胶光学特性垂直分布
徐栋夫,曹萍萍,王源程
(成都市气象局,成都 611130; 四川省气象台,成都 610072; 成都市环境保护科学研究院,成都 610072; 高原与盆地暴雨旱涝灾害四川省重点实验室,成都 610072)
Study of the Vertical Distribution of Aerosol Optical Properties During a Heavy Pollution Event in Chengdu
XU Dongfu,CAO Pingping,WANG Yuancheng
(Chengdu Meteorological Bureau, Chengdu 611130; Sichuan Meteorological Observatory, Chengdu 610072; Chengdu Academy of Environmental Sciences, Chengdu 610072; Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province, Chengdu 610072)
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投稿时间:2019-03-15    修订日期:2020-02-28
中文摘要: 利用微脉冲激光雷达观测数据、PM2.5浓度数据、地面气象观测资料和探空数据对成都2017年1月1—6日连续出现的重污染过程进行分析研究。结果表明:激光雷达反演的消光系数演变与PM2.5浓度值变化对应一致,PM2.5浓度升高,近地面消光系数增大;反之,则近地面消光系数减小。对于此次过程,在无冷空气影响时,混合层高度和相对湿度的日变化对消光系数廓线有明显影响,混合层高度降低,大气环境容量减小,相对湿度增加,气溶胶吸湿增长,消光系数增大,地面污染加重。天空状况对气溶胶垂直分布影响显著,晴天或多云天气,早晨强逆温使得水汽和大量气溶胶集中在逆温层顶以下区域,地面污染严重;中午混合层发展,使得混合层内的气溶胶均匀混合,气溶胶层变厚,近地面消光系数显著减小,地面污染减轻。在前一日为晴天或多云天气,当天为阴天时,早上气溶胶明显分为两层,一层在近地面,另一层在残留层顶附近;中午由于垂直湍流增强,一部分残留层气溶胶向下混合至混合层内,使得混合层内的气溶胶粒子增多,地面污染加重,消光系数明显增加。近地面强逆温层、混合层高度降低、残留层气溶胶向下混合、相对湿度增加均是导致地面污染加重的原因。
Abstract:An event of heavy pollution in Chengdu during 1-6 January 2017 was analyzed in this study by using the data of micro-pulse lidar, the concentration of PM2.5, surface meteorological observations and vertical soundings. The results show that the extinction coefficient calculated by the lidar data is highly consistent with the change of PM2.5 concentration. When PM2.5 concentration increases, the near-surface extinction coefficient increases. Conversely, the near-surface extinction coefficient decreases. For this particular case, when there is no influence of cold air, diurnal variations of mixing layer height and relative humidity have obvious influence on the profile of extinction coefficient. The decrease of mixing layer height and the increase of relative humidity result in the increase of extinction coefficient and the aggravation of the pollution. The sky condition has a significant effect on the vertical distribution of aerosol. In sunny or cloudy days, the water vapor and a large number of aerosols concentrate in the area below the top of inversion layer because of the strong inversion in the morning. As the aerosol layer thickens, the near-surface extinction coefficient decreases significantly due to the evenly mixing of aerosols in the mixed layer with the development of mixed layer at noon. When the previous day was sunny or cloudy and the very day is overcast, the aerosol is obviously divided into two layers in the morning, one is near the ground and the other one is near the top of the residual layer. Part of residual layer aerosol is mixed downward into the mixed layer because the vertical turbulence at noon makes the extinction coefficient in the mixed layer increase significantly. The strong inversion layer near the surface, the decrease of the height of the mixed layer, the downward mixing of the residual aerosol layer and the increase of relative humidity are all responsible for the aggravation of the pollution.
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基金项目:高原与盆地暴雨旱涝灾害四川省重点实验室科技发展基金项目(省重实验室2018-青年-23)资助
引用文本:
徐栋夫,曹萍萍,王源程,2020.成都一次重污染过程的气溶胶光学特性垂直分布[J].气象,46(7):948-958.
XU Dongfu,CAO Pingping,WANG Yuancheng,2020.Study of the Vertical Distribution of Aerosol Optical Properties During a Heavy Pollution Event in Chengdu[J].Meteor Mon,46(7):948-958.