Aerosol mass loading over the marine environment of Arabian Sea during ICARB: Sea-salt and non-sea-salt components

Abstract

Mass loading and chemical composition of atmospheric aerosols over the Arabian Sea during the pre-monsoon months of April and May have been studied as a part of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB). These investigations show large spatial variabilities in total aerosol mass loading as well as that of individual chemical species. The mass loading is found to vary between 3.5 and 69.2 μg m−3, with higher loadings near the eastern and northern parts of Arabian Sea, which decreases steadily to reach its minimum value in the mid Arabian Sea. The decrease in mass loading from the coast of India towards west is estimated to have a linear gradient of 1.53 μg m−3/° longitude and an e−1 scale distance of ∼2300 km. SO42−, Cl− and Na+ are found to be the major ionic species present. Apart from these, other dominating watersoluble components of aerosols are NO3− (17%) and Ca2+ (6%). Over the marine environment of Arabian Sea, the non-sea-salt component dominates accounting to ∼76% of the total aerosol mass. The spatial variations of the various ions are examined in the light of prevailing meteorological conditions and airmass back trajectories.