Influence of natural and anthropogenic emissions on aerosol optical properties over a tropical urban site — A study using sky radiometer and satellite data

Atmospheric aerosols are important aspects of climate research due to their impact on radiative forcing. In the present study, the aerosol optical depth (AOD), the Ångström exponent (α) and the single scattering albedo (SSA) over the urban region of Hyderabad, India, were examined using Sun/Sky radiometer measurements during January–December, 2008. AOD showed higher values on certain Julian days coinciding with the occurrence of wintertime dust storm events in the Gulf Region and biomass burning due to forest fires over Indian Region. The AOD values during wintertime dust event are about ~ 55% higher than those on normal days. The SSAs show positive and negative trends in α (R2 = 0.71) and black carbon (BC) aerosols (R2 = 0.44), respectively. The aerosol size distribution shows a bimodal pattern with fine (~ 0.15 μm) and coarse (~>7 μm) mode during January–December, 2008. The MODIS AOD showed positive correlation with sky radiometer-derived AOD values (R2 = 0.68).