Seasonal Variation of Sulphate Aerosols and its Optical Properties Over Karachi During 2018

Sulphate Aerosols and Optical Properties

Abstract

Seasonal variation of sulphate aerosols along with its optical properties and its dependence upon meteorological parameters are studied over Karachi, Pakistan during 2018 by using Giovanni data, where MEERA-2 analysis has been performed using OpenGrADS. Analysis of results showed that mass concentration (5-13 µg/m3) and column density (19-24.5 mg/m2) of sulphate aerosol and its extinction factor (0.18) is high in winter and autumn seasons showing dependence on biomass burning and fossil fuel combustion in the industrial sector. Low precipitation and wind speed favour the accumulation of pollutants and their transport from Nawabshah and Hyderabad to Karachi. On the other hand, in summer and spring low biomass burning, small retention time due to frequent precipitation, causing washing of air and reversal of wind direction are all the factors preventing the accumulation of pollutants in the area. This cause a decrease in the mass concentration (1.9-3 µg/m3), density (9.8-13 mg/m2) and extinction factor (0.06) of sulphate aerosols in the troposphere.