THE INFLUENCE OF FOREST AND PEATBOG FIRES ON THE OPTICAL AND RADIATIVE REGIMES OF THE ATMOSPHERE AND RADIATIVE FORCING OVER CENTRAL RUSSIA

摘要

We analyzed radiation and optical properties of the atmosphere during severe fire events over Central Russian plain in 2002. The fire "cloud" was characterized by high aerosol optical thickness (AOT) up to 3 at 500 nm with mean AOT500 of 1.02, high values of single scattering albedo (SSA(velence)0.95) according to retrievals from AERONET CIMEL sun and sky photometer as well as by high concentration of optically effective gas species. Distinctive spectral features of solar irradiance attenuation include larger drops in the UV, when compared with typical clear sky conditions (-24percent for total and -38percent for UV irradiance) with decreases in both direct and diffuse components of UV. This is in agreement with model results if we take into account additional absorption by gases (mainly, O_(3) and NO_(2)) and reduce aerosol single scattering albedo in the UV (0.89-0.9 for <320 nm). Radiation forcing efficiency is about -39 W/m~(2) at TOA and -80 to -100 W/m~(2) at ground. The radiation budget of the mean fire "cloud" averaged over August 2002 is distributed among reflection, transmission and absorption as 26percent, 58percent, and 29percent. The absorption due to smoke aerosol is about 5percent and the absorption by NO_(2) comprises about 2percent. Both reflection and absorption increase by approximately 4percent, compared with typical conditions without fires.