Articles | Volume 5, issue 8
Atmos. Meas. Tech., 5, 1973–2002, 2012
Atmos. Meas. Tech., 5, 1973–2002, 2012

Research article 17 Aug 2012

Research article | 17 Aug 2012

Intercomparison of desert dust optical depth from satellite measurements

E. Carboni1, G. E. Thomas1, A. M. Sayer1,2,11, R. Siddans2, C. A. Poulsen2, R. G. Grainger1, C. Ahn3, D. Antoine4, S. Bevan5, R. Braak6, H. Brindley7, S. DeSouza-Machado8, J. L. Deuzé9, D. Diner10, F. Ducos9, W. Grey5, C. Hsu11, O. V. Kalashnikova10, R. Kahn11, P. R. J. North5, C. Salustro11,**, A. Smith1, D. Tanré9, O. Torres11, and B. Veihelmann6,* E. Carboni et al.
  • 1Atmospheric, Oceanic and Planetary Physics, Clarendon Laboratory, University of Oxford, Oxford, UK
  • 2Space Science and Technology Department, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, UK
  • 3Science Systems and Applications, Maryland, USA
  • 4Laboratoire d'Océanographie de Villefranche (LOV), Centre National de la Recherche Scientifique (CNRS) and Université Pierre et Marie Curie, Paris 06, Villefranche-sur-Mer, France
  • 5Geography Department, College of Science, Swansea University, UK
  • 6Royal Netherlands Meteorological Institute (KNMI), The Netherlands
  • 7Imperial College, London, UK
  • 8University of Maryland Baltimore County, USA
  • 9LOA, Université Lille-1, France
  • 10Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
  • 11NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • *now at: Science, Applications and Future Technologies Department, ESA/ESTEC, The Netherlands
  • **now at: Risk Management Solutions, Inc., Newark, California, USA

Abstract. This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD) during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify the differences between current datasets. The satellite instruments considered are AATSR, AIRS, MERIS, MISR, MODIS, OMI, POLDER, and SEVIRI. An interesting aspect is that the different algorithms make use of different instrument characteristics to obtain retrievals over bright surfaces. These include multi-angle approaches (MISR, AATSR), polarisation measurements (POLDER), single-view approaches using solar wavelengths (OMI, MODIS), and the thermal infrared spectral region (SEVIRI, AIRS). Differences between instruments, together with the comparison of different retrieval algorithms applied to measurements from the same instrument, provide a unique insight into the performance and characteristics of the various techniques employed. As well as the intercomparison between different satellite products, the AODs have also been compared to co-located AERONET data. Despite the fact that the agreement between satellite and AERONET AODs is reasonably good for all of the datasets, there are significant differences between them when compared to each other, especially over land. These differences are partially due to differences in the algorithms, such as assumptions about aerosol model and surface properties. However, in this comparison of spatially and temporally averaged data, it is important to note that differences in sampling, related to the actual footprint of each instrument on the heterogeneous aerosol field, cloud identification and the quality control flags of each dataset can be an important issue.