Zonal Distribution of Aerosol Physicochemical Characteristics in the Eastern Atlantic

Abstract

Based on long-term (2004–2016) expedition studies, statistical generalization and zoning of aerosol physicochemical characteristics in the eastern Atlantic (from the English Channel to Antarctica) are performed. For six latitudinal zones of the Atlantic and Southern Oceans (>45°N; 20°–45°N; 0°–20°N; 0°–20°S; 20°–55°S; >55°S) the average values of the main aerosol characteristics are presented, i.e., atmospheric aerosol optical depth (AOD), fine and coarse AOD components, particle number concentrations, and mass concentrations of aerosol, black carbon, and water-soluble ions (Na⁺, Mg²⁺, Cl⁻, K⁺, Ca²⁺, \(\rm{NH}_4^+, \rm{NO}_3^-, \rm{SO}_4^{2-}\)), as well as of gas admixtures (SO₂, HCl, HNO₃, NH₃). It is shown that the zonal variability range of optical and microphysical aerosol characteristics is about an order of magnitude: the largest (minimal) average values are observed in the tropical zone (over Southern Ocean). The zonal differences (a factor of 1.3 to 4.3) in concentrations of ions and gas admixtures are much smaller and comparable to synoptic-scale variations. The concentrations of “marine” ions are maximal over the Southern Atlantic, and those of “continental” ions in the Northern hemisphere tropical and subtropical zones; the concentrations of all ions are minimal over the Southern Ocean. The specific features of geographic distribution of gas admixtures are noted: the maximal concentrations of HCl and NH₃ are observed over the Southern Atlantic, those of SO₂ and HNO₃ near Europe, and the lowest level is observed in the tropical zone.