[MAIAC AOD and PM Mass Concentrations Characteristics and Correlation Analysis in Beijing-Tianjin-Hebei and Surrounding Areas].

Based on the MAIAC AOD and PM mass concentration data for the Beijing-Tianjin-Hebei region and surrounding areas from 2014 to 2018, the temporal and spatial differences in Aerosol Optical Depth (AOD) and PM mass concentrations were explored and their correlation was analyzed by linear regression. The results show that the daily average concentration of PM exceeds the standard for 33% and 57% of measurements based on the daily average standard values of the World Health Organization IT.1 and IT.2, respectively, indicating serious pollution levels. The annual average concentrations of PM and Terra and Aqua MAIAC AOD all show downward trends. The PM concentrations are high in winter and spring and low in summer and autumn; Terra and Aqua AOD values are high in spring and summer and low in autumn and winter. The seasonal and annual average concentrations of PM and AOD all show the regional pattern of "low in the north and high in the south". High-value areas are mainly located in southern Hebei, southwestern Shanxi, western Shandong, and northern Henan, while low-value areas are mainly located in northwestern Shanxi, northern Hebei, and eastern Shandong. The annual average concentration of PM is between 27 and 99μg·m, and the annual average AOD is between 0.20 and 0.69. The correlation between Aqua AOD and PM concentration is strong whereas and the correlations between Terra AOD, Aqua AOD, and PMvary significantly in different seasons; overall, correlations are strongest in spring and winter and weakest in summer and autumn. After vertical-humidity correction, the correlation between satellite AOD and PM data is significantly improved.