Spatial distribution and temporal variation of aerosol optical depth and radiative effect in South China and its adjacent area

The spatio-temporal characteristics of aerosol loading over South China from 2001 to 2016 were investigated using aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and NO2 from the Ozone Monitoring Instrument (OMI). AOD values were high in the central part and low in the southeast and northwest parts of South China. High AOD (larger than 0.7) were found in the Pearl River Delta, Nanning, and Hanoi (Vietnam). The seasonal average AOD was high in spring (approximately 0.7) and low in winter (approximately 0.4). Generally, an increasing trend of AOD was found from 2001 to 2004 and a decreasing trend from 2004 to 2016 in the continent due to the change in pollutant discharging, which was verified by annual NO2 data. Furthermore, the aerosol radiative effect (ARE) was calculated using the Mesoscale Atmospheric Global Irradiance Code (MAGIC) and MODIS AOD time series. The spatial distribution and temporal variation of ARE at surface showed similar patterns to AOD, with high values occurring in the Pearl River Delta (−39 W/m2), Hanoi (−36 W/m2), and Nanning (−30 W/m2). From 2001 to 2016, ARE at surface in South China decreased by approximately 4 W/m2 with the highest value (−24.75 W/m2) occurring in 2007.