Optical Properties of Smoke Aerosol over ZSS in July-September 2002 from MFRSR Measurements
Sviridenkov, M.A., Anikin, P.P., Romashova, E.V., Isakov, A.A., and Emilenko, A.S., A.M. Obukhov Institute of Atmospheric Physics RAS, Moscow, Russia
Thirteenth Atmospheric Radiation Measurement (ARM) Science Team Meeting
Regular measurements of aerosol optical thickness at Zvenigorod Scientific Station (ZSS) of the Institute of Atmospheric Physics with MFRSR instrument were started in 2000. In summer and autumn of 2002, peatbog and forest fires in Central Russia produced a great amount of smoke aerosol which covered significant areas not only in the Europian Territory of Russia, but even in West Siberia. Maximal values of aerosol optical thickness over ZSS in visible region exceeded 2. The Angstrom exponent, characterizing the spectral behavior of the optical thickness, varied from 1.7 in July and August to 1.2 in September. MFRSR data were inverted to the size distributions of submicron aerosol. It was revealed that modal radius of volume size distribution lies in the range of 0.1 0.2 micron. Data of measurements in the atmospheric column were compared with nephelometer observations of near-surface aerosol, and height of smoke aerosol layer was estimated. It changed from several kilometers to hundreds meters. One of the main parameters, determining the effects of smoke aerosol on atmospheric radiation, is the single scattering albedo (SSA). Estimates of SSA from MFRSR data were obtained using diffuse-direct method. For this purpose, the previously suggested analytical approximation of the ratio of diffuse to direct solar radiation flux was adjusted for the optical thickness up to 3. Our estimates show that the observed smoke aerosol has a relatively weak absorption with SSA within 0.96-0.98. This result agrees with the data of ground-based measurements of soot concentration in aerosol samples.
Note: This is the poster abstract presented at the meeting; an extended version was not provided by the author(s).
