Effects of Atmospheric Aerosol Types on Ultraviolet Flux at Different Stations in the Indo-Gangetic Plain

Abstract

Atmospheric aerosols play a crucial role in the scattering and absorption of solar radiation, directly influencing the UV flux reaching the Earth’s surface. This study investigates the impact of different atmospheric aerosol types on the ultraviolet (UV) flux at four stations over the Indo-Gangetic plain (IGP). For this study, high-resolution 1° × 1° UVA and UVB data were obtained from Clouds and the Earth’s Radiant Energy System (CERES). Various aerosol types present in the atmosphere were categorized based upon their optical properties and their quantitative influence on UVA and UVB flux was examined. Ground-level aerosol products were obtained from the NASA-based Aerosol Robotic Network (AERONET) at four stations in the IGP. Based on the optical properties of aerosols (fine mode fraction, single scattering albedo, aerosol optical depth and angstrom exponent), four distinct atmospheric aerosol types were inferred, namely dust-dominant (DT), polluted-continental-dominant (PCD), black-carbon-dominant (BCD), and organic-carbon-dominant (OCD). It is observed that the AOD of different aerosol types when separated do not seem to have made significant effects on UVA/B radiation (except at Kanpur), possibly due to the statistically smaller data set. For the entire combined AOD, the effects on UVA/B became quite significant at all the stations, which shows that a unit rise in AOD leads to a reduction of 5–7 Wm−2 in UVA and 0.14–0.23 Wm−2 in UVB.

Keywords

• aerosol types
• UVA
• UVB
• AERONET
• CERES