The empirical relationship between PM2.5 and AOD in Nanjing of the Yangtze River Delta

摘要

Ground-based Aerosol optical properties and PM2.5 concentrations in an industrial area in Nanjing were measured and analyzed from May 2013 to May 2015. The annual mean of the aerosol optical depth (AOD) at 550??nm was 1.04???±??0.63. The annual mean of the Angstrom exponent (?±) was 1.03???±??0.23. The annual PM2.5 concentration was 62???±??13????g??ma??3. There were significant correlations between the PM2.5 concentration and the AOD. The linear regression functions of the daily PM2.5 concentration (y) with the ground-based AOD (x) and the MODIS AOD (x) were y??=??55.70x??+??25.60 (R2??=??0.53) and y??=??63.84x??+??39.33 (R2??=??0.56), respectively. The results demonstrated significant differences in the slopes and intercepts of the linear regression functions for different seasons. The distribution of PM2.5 was retrieved by the seasonal functions between the ground-based PM2.5 and the MODIS AOD on sunny days in the region. The MODIS-derived PM2.5 concentrations in the north of Jiangsu and parts of Shandong and Henan were generally higher than those in the hilly lands of the south of Anhui and the northwest of Zhejiang. There was a high-PM2.5 area anchored over the industrial area. The particle pollution was more serious in spring and winter than in autumn and summer. The MODIS-derived PM2.5 concentration in urban and industrial areas was higher than 80????g??ma??3 during spring and winter. The retrieved PM2.5 values had the highest absolute error (+17????g??ma??3) in summer and the lowest (+2????g??ma??3) in winter, and the average relative error of the seasonal PM2.5 concentration was 15%???±??10%.