Absorption, scattering and single scattering albedo of aerosols obtained from in situ measurements in the subarctic coastal region of Norway

Abstract. In situ measurements of aerosol optical properties were made in summer 2008 at the ALOMAR station facility (69°16 N, 16°00 E), located at a rural site in the North of the island of Andøya (Vesterålen archipelago), about 300 km north of the Arctic Circle. The extended three months campaign was part of the POLAR-CAT Project of the International Polar Year (IPY-2007-2008), and its goal was to characterize the aerosols of this sub-Arctic area which frequently transporte to the Arctic region. The ambient light-scattering coefficient, σ_s(550 nm), at ALOMAR had a hourly mean value of 5.412 Mm⁻¹ (StD = 3.545 Mm⁻¹) and the light-absorption coefficient, σ_a(550 nm), had an hourly mean value of 0.400 Mm⁻¹ (StD = 0.273 Mm⁻¹). The scattering/absorption Ångström exponents, α_s,a, are used for detailed analysis of the variations of the spectral shape of σ_s,a. The single scattering albedo, &omega₀, ranges from 0.622 to 0.985 (mean = 0.913, StD = 0.052) and the relation of this property to the absorption/scattering coefficients and the Ångström exponents is presented. The relationships between all the parameters analyzed, mainly those related to the single scattering albedo, allow us to describe the local atmosphere as extremely clean.