陕西关中气溶胶对大气能见度的影响研究

Study of Influence of Aerosol on Atmospheric Visibility in Guanzhong Region of Shaanxi Province

为了研究大气污染对能见度的影响,利用MODIS卫星气溶胶光学厚度(Aerosol Optical Depth,AOD)产品、陕西关中地区43个气象观测站能见度资料、西安泾河太阳光度计CE318气溶胶观测资料以及泾河站风速、相对湿度、能见度观测资料,分别分析了卫星MODIS/AOD和地基CE318/AOD与能见度、低能见度日数的关系以及在不同风速、相对湿度时AOD与能见度的关系。结果表明,陕西关中MODIS/AOD的空间分布与能见度分布具有明显对应关系,冬、春季AOD与08:00(北京时,下同)能见度相关最好,夏、秋季AOD与14:00能见度相关最好。去除降水因素后,空气中颗粒物污染是造成秋、冬季出现低能见度的主要原因。地基观测的气溶胶波长指数在0.8~1.2之间时对能见度的影响最大。空气中颗粒物造成的能见度下降与相对湿度密切相关,湿度越大,能见度下降越明显。风速小,大气中的颗粒物容易聚集,使能见度变差;风速大,有利于空气中颗粒物扩散,使能见度得到改善。用AOD估算能见度时,需要考虑大气相对湿度和风速的影响。

To further study the influence of air pollution on atmospheric visibility,using the products of aerosol optical depth( AOD) of MODIS,the observed visibility data at 43 meteorological stations,and measured AOD using CE318,wind speed,relative humidity and visibility data at Jinghe in Xi'an,the relationship between the distribution of MODIS /AOD and visibility,the relationship between MODIS /AOD and the days of visibility less than 10 km in autumn and winter,and the relationship between MODIS /AOD and visibility under different wind speed,relative humidity,have been analyzed. The results show the distribution of MODIS /AOD is correspond well with the distribution of visibility. The correlation coefficient of MODIS /AOD and visibility at 08: 00 in winter and spring is better than other seasons. While the correlation coefficient of MODIS /AOD and visibility at 14:00 is better in summer and autumn. Air particulate pollution is the most important factor which causes lower visibility in autumn and winter except precipitation. When ngstrom range from 0. 8 to 1. 2,aerosols impact on visibility distinctly. The deterioration of visibility caused by air polluted is closely related with relative humidity,higher relative humidity causing more visibility decline. When wind speed is lower,particles in air accumulate easily and lead to visibility deterioration. When wind speed is higher,air pollutants diffuse easily and the visibility improve quickly. Estimating visibility using AOD must consider the influence of relative humidity and wind speed on them.