Spatial distributions and temporal variations of atmospheric aerosols and the affecting factors: a case study for a region in central China

Abstract

Using Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol data, temporal variations and the spatial distribution of aerosol optical depth (AOD or τ) over the Hubei Province in China were investigated from 2003 to 2008. self-organizing maps (SOMs) and linear models were further used to analyse the relationships between AODs and elevation, normalized difference vegetation index (NDVI) and population density. The results were as follows: high AOD values were observed in south-central areas with lower elevations, lower NDVI and larger population densities, whereas low AOD values were observed in the western, northeastern and southeastern areas. The highest AOD values were observed in spring; summer was characterized by lower AOD values, but also the largest ratio of fine particles; in autumn, the coverage of AOD was only smaller than spring with most being fine particles; in winter, coarse particles were dominant when AOD values were the lowest. The AOD monthly average rose substantially in the winter–spring season and dropped sharply in the spring–winter season. Based on these data, both SOMs and linear models show that AOD distribution is influenced by the complex interactions that occur among various elements. The annual AODs are negatively related to ln(elevation) and NDVI and positively related to ln(population density). The ln(elevation) factor affects aerosol distribution more than do the other two factors. Compared to fine-particle aerosols, the selected three factors have a greater impact on the coarse particles.