Home – Home – Jornals – Atmospheric and Oceanic Optics 2017 number 1

We discuss the results of studying the physical-chemical composition of the atmospheric aerosol during expedition onboard RV “Akademik Nikolaj Strakhov” carried out during winter of 2015/2016 on the route from Colombo to Kaliningrad (via Suez Canal). In comparison with the Mediterranean Sea and Atlantic (near Europe), the atmosphere of the Arabian and Red Seas was characterized by higher values of most aerosol characteristics: 3-5 times larger aerosol optical depth (AOD), 4 times larger aerosol number concentration, 1.5 times larger concentrations of continent- and sea-derived ions, as well as more abundant gaseous admixtures (SO₂, HCl, HNO₃, NH₃). At the same time, two seas of the Indian basin show substantial differences in aerosol composition, caused by outflows of aerosols of different types from the continents. The largest concentrations of black carbon (2.14 µg · m^-3, on the average), sea-derived ions (Na⁺, Cl^-, Mg²⁺), and NH₃ are observed over the Arabian Sea; and larger values of fine component of AOD and concentrations of “continental” ions (SO₄^2-, Ca²⁺, NO₃^-, NH₄⁺) and gaseous admixtures SO₂, HCl, HNO₃ are found over the Red Sea. With respect to ion composition of aerosol, most stable concentrations are noted in Ca²⁺ ions (less than 15% difference among the seas), and maximal spatial variations are found in NH₄⁺ ions (a difference is up to a factor of 40).