Vol. 23, issue 06, article # 5

Abstract:

We discuss the specific features of the aerosol radiative characteristics in situations of forest fire smokes and under usual (background) conditions in Siberia. The analysis is based on the multiyear measurements of aerosol optical depth (AOD) of the atmosphere in the wavelength range 0.37-4mm. For two types of conditions ("smoke/background"), we present the statistical charac-teristics of the spectral AOD, Angstrom parameters, finely and coarsely dispersed AOD components, retrieved parameters of the aerosol microstructure, and aerosol radiative forcing. It is shown that, in the 0.5-mm region, AOD under smoke conditions increases, on the average, by a factor of 2.7, finely dispersed component increases by a factor of 3, and coarsely dispersed component increases by a factor of 1.5. The choice of the input parameters for the radiation calculations is substantiated; it is based on the combination of multiyear ground-based observations, satellite measurements, and model data. It is shown that the aerosol radiative forcing at the bottom of the atmosphere is -22 W/m² under background conditions, it increases to -50 W/m² in the smoke situations, and it can reach -140 W/m² and more for strong smoke.

Keywords:

aerosol optical depth, biomass burning aerosol, background conditions, aerosol radiative forcing, numerical simulation