Investigation of curvature effect of Ångström exponent to classify the aerosol types over the region of interest (88°-98° E and 20°-30° N)

Abstract

The present study focuses on the investigation for discrimination of the aerosol types using the curvature effect of Ångström exponent for different areas within the region of interest (88°-98° E and 20°-30° N). There are very few studies on aerosol optical properties and on the size distribution characteristics of aerosols over this region. The fast socio-economic expansion in the last few years has been sped up the emissions of anthropogenic aerosols in the study region. Aerosol optical depth (AOD) and Ångström exponent (α) values used in the present study were taken from Multi-angle Imaging SpectroRadiometer, onboard Aqua, and Terra satellite sensor product for four different domains D-1 (Lat: 88°-93°E, Lon: 25°-30°N), D-2 (Lat: 93°-98°E, Lon: 25°-30°N), D-3 (Lat: 88°-93°E, Lon: 20°-25°N) and D-4 (Lat: 93°-98°E, Lon: 20°-25°N) of Indian subcontinent. AOD and α over the four domains were characterized on an annual basis. α was calculated for 445–557 nm and 672–867 nm wavelength pairs and correlated for the four domains. The observations indicate that the spectral curvature can provide valuable information about the aerosol types which can effectively discriminate the effect of the aerosol types. From the analysis, it noticed that the dominance of fine mode particle shows a negative curvature, while the coarse mode aerosols give a positive curvature. From the analysis, we found that, both the coarse and fine mode aerosol particles dominated over D-1, D-2, and D-4 regions, while the dominance of coarse mode aerosols alone has been observed over the D-3 regions.