A meridional profile of the chemical composition of submicrometre particles over the East Atlantic Ocean: regional and hemispheric variabilities

Abstract

Within the framework of SWEDARP (Swedish Antarctic Program) 92/93 an aerosol sampling program was carried out on board of M/S Polarbjörn which carried staff and material to the Nordic Antarctic field exercises during the Austral summer 1992/1993. The cruise started 11 November 1992 from Oslo, went via Cape Town to Antarctica, and then back to Cape Town where the ship arrived on 4 January 1993. During the cruise, a meridional profile of physical and chemical submicrometre aerosol properties was derived covering the East Atlantic Ocean from 60°N to 70°S. The multicomponent aerosol data set combined with a trajectory analysis revealed a systematic meridional distribution of aerosol sources over the Atlantic that covered European and African continental plumes and, south of 15°S, a largely biologically controlled marine aerosol. Median number concentrations calculated over the whole cruise spanned a factor of 20 between 2000 and 100 cm⁻³, while total analyzed mass concentrations ranged between 7800 and 40 ng m³. From the biologically dominated subset of the data in the southern hemisphere, relationships were developed that allowed an apportionment of the observed sulfate and ammonium concentration to biogenic and anthropogenic sources over the whole meridional aerosol profile.