The direct radiative effect of biomass burning aerosols over southern Africa S. J. Abel1,2, E. J. Highwood1, J. M. Haywood2, and M. A. Stringer1 1Department of Meteorology, University of Reading, UK 2Met Office, Exeter, UK
Abstract. A multi-column radiative transfer code is used to assess the direct radiative
effect of biomass burning aerosols over the southern African region during
September. The horizontal distribution of biomass smoke is estimated from two
sources; i) General Circulation Model (GCM) simulations combined with
measurements from the Aerosol Robotic Network (AERONET) of Sun photometers;
ii) data from the Moderate resolution Imaging Spectrometer (MODIS) satellite.
Aircraft and satellite measurements are used to constrain the cloud fields,
aerosol optical properties, vertical structure, and land surface albedo
included in the model. The net regional direct effect of the biomass smoke is
-3.1 to -3.6 Wm-2 at the top of atmosphere, and -14.4 to
-17.0 Wm-2 at the surface for the MODIS and GCM distributions of
aerosol. The direct radiative effect is shown to be highly sensitive to the
prescribed vertical profiles and aerosol optical properties. The diurnal
cycle of clouds and the spectral dependency of surface albedo are also shown
to play an important role.
Citation: Abel, S. J., Highwood, E. J., Haywood, J. M., and Stringer, M. A.: The direct radiative effect of biomass burning aerosols over southern Africa, Atmos. Chem. Phys., 5, 1999-2018, doi:10.5194/acp-5-1999-2005, 2005.