Analysis of aerosol characteristics and their relationships with meteorological parameters over Anhui province in China

Abstract

The characteristics of Aerosol Optical Depth (AOD) and Ångström exponent are analyzed and AODs are compared with CE318 measurements from 2001 to 2009 over Anhui province in China, with an evaluation of potential contributing factors, including regional burning emissions and meteorology. The result indicates that MODIS AODs (Collection 5, C005) are in good agreement with those from CE318 with correlation coefficient of above 0.80 and RMS of below 0.21 in Anhui. Most of MODIS cases fall in the range of ∆τ=±0.05±0.20τ at four AERONET sites. Aerosol optical properties show a notable spatial–temporal distribution feature in Anhui. The values of lower AOD and higher Ångström exponent both appear at southern mountain area. We document seasonal variations in patterns of AOD and Ångström exponent in Anhui, for which peak values respectively occur in June and August. Time series plots for AOD and fire pixel counts are produced to provide a better understanding of influence of burning emission for aerosol. Agricultural residue burning occurs seriously in June, which leads to appearance of AOD peak values. The results between AODs and meteorological parameters show good relationships at Fuyang. Wind speed and wind direction can strongly influence aerosol optical depth and its size, meanwhile, relative humidity and visibility respectively have positive and negative correlation with AODs. Mixed layer depths and AODs have similar monthly variation trend. We use HYSPLIT model for trajectory analysis to reveal the origins of air masses for different levels AODs and Ångström exponent, with the aim of discriminating contributions of different sources.