Long-term simulations (2001–2006) of biomass burning and mineral dust optical properties over West Africa: comparisons with new satellite retrievals F. Malavelle1,2, M. Mallet1,2, V. Pont1,2, C. Liousse1,2, and F. Solmon3 1Université de Toulouse, UMR5560, UPS, LA (Laboratoire d'Aérologie), 14 avenue Edouard Belin, 31400 Toulouse, France 2CNRS, LA (Laboratoire d'Aérologie), 31400 Toulouse, France 3International Centre for Theoretical Physics, Trieste, ESP (Earth System Physics), Italy
Received: 08 September 2011 – Accepted: 20 September 2011 – Published: 25 October 2011
Abstract. The West African region is characterized by large concentrations of smoke
and biomass burning aerosols, which could significantly modify the regional
radiative budget and the hydrological cycle. Here, we propose long-term
(2001–2006) RegCM simulations of aerosol optical properties over West Africa
together with their spectral dependences. Results of simulations are
evaluated at local and regional scale by using surface network
(AERONET/PHOTON) and remote sensing observations (MODIS, MISR, OMI)
especially during the dry season, December-January-February, DJF. New
original satellite retrievals are tested and compared to RegCM simulations.
Concerning AOD, we obtain values in agreement with AERONET/PHOTON
observations at the local scale but some differences clearly appear between
simulated AOD and regional MISR, OMI and MODIS view, especially over (1) the
central Africa and (2) the gulf of Guinea during DJF. Concerning simulated
SSA (for visible wavelengths), our results display (1) comparable values
with level 2 AERONET/PHOTON local observations together with (2) non
negligible differences with satellite (MODIS Deep blue, OMI and MISR
products) observations. In most cases, satellite SSA is found to be higher
than those simulated by RegCM and retrieved through AERONET/PHOTON network.
In parallel, we also note significant differences on retrieved SSA from each
satellite (OMI, MISR, MODIS Deep Blue) remote sensing techniques over this
specific region. Finally, our work highlights that the spectral dependence
of aerosol optical properties is a useful parameter to adapt so that modeled
simulations should be be better evaluated and constrained.
Citation: Malavelle, F., Mallet, M., Pont, V., Liousse, C., and Solmon, F.: Long-term simulations (2001–2006) of biomass burning and mineral dust optical properties over West Africa: comparisons with new satellite retrievals, Atmos. Chem. Phys. Discuss., 11, 28587-28626, doi:10.5194/acpd-11-28587-2011, 2011.