Vol. 22, issue 07, article # 3

Abstract:

Seasonal variability of the vertical profiles of concentrations of aerosol and soot, soot fraction, single scattering albedo, and absorption index of particulate matter are studied based on long-term airborne measurements of the scattering coefficient of dry matter of aerosol particles at a wavelength of 0.51 m and the mass concentration of soot in the troposphere up to a height of 7 km in southern part of Novosibirsk region. It is shown that the lower (up to 1.5 km) and upper (above 1.5 km) layers of the troposphere are extremely different in absorption properties of aerosol. In the lower layer, in winter and autumn, mean values of the soot fraction decrease with height in wide range from 13 to 5%. The values of albedo increase with height, varying in the range from 0.8 to 0.94. In the lower layer, in winter, aerosol particles have strong absorption. The value of the absorption index has the greatest values, about 0.09, in the near-ground layer, and decreases with height to values of 0.03. In the upper layer, the values of the soot fraction vary weaker, in the range 2-5%. The range of seasonal and altitudinal variations of the albedo becomes narrower (0.92-0.97), and the values of the absorption index vary in the range from 0.03 to 0.01, i.e., aerosol particles in the upper air layer are comparatively weakly absorbing. Estimates of variability of the aerosol radiative parameters evidence a certain independence of the behavior of the soot component at formation of the vertical profiles of the aerosol and soot concentrations.

Keywords:

submicron aerosol; soot; troposphere; altitude profiles; relative soot content; single scattering albedo