Diurnal variations of the submicron aerosol and black carbon in the near-ground layer

Abstract

Peculiarities of seasonal variability of diurnal variations of the mass concentrations of submicron aerosol and black carbon (BC) in the near-ground layer have been analyzed based on the measurements carried out in 1997–2008 at the aerosol station of the Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences (Tomsk). The shape of aerosol and BC diurnal variations are the same for all seasons, with morning and evening maxima and nighttime and daytime minima. The maxima in the diurnal variations of aerosol concentration approach each other in winter and move away from each other in summer. Shape stability of the BC diurnal variations in different seasons is an indicator of stable diurnal dynamics of the aerosol absorption coefficient in the visible spectrum. Some differences in the diurnal variations of aerosol and BC make it possible to draw a conclusion about the presence of a certain BC fraction in the form of external admixture. All extremums of the diurnal aerosol and BC variations clearly manifest in the cloudless atmosphere; however, the diurnal variations become smooth in continuous cloudiness. In this case, the morning maximum of aerosol becomes statistically insignificant in different seasons.