Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 5 3 2005 10.5194/acp-5-611-2005 http://www.atmos-chem-phys.net/5/611/2005/ http://www.atmos-chem-phys.net/5/611/2005/acp-5-611-2005.html http://www.atmos-chem-phys.net/5/611/2005/acp-5-611-2005.pdf 611 622 2005-03-01 Column ozone and aerosol optical properties retrieved from direct solar irradiance measurements during SOLVE II W. H. Swartz J.-H. Yee R. E. Shetter S. R. Hall B. L. Lefer J. M. Livingston P. B. Russell E. V. Browell M. A. Avery The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA National Center for Atmospheric Research, Boulder, Colorado, USA SRI International, Menlo Park, California, USA NASA Ames Research Center, Moffett Field, California, USA NASA Langley Research Center, Hampton, Virginia, USA now at: University of Houston, Department of Geosciences, Houston, Texas, USA Direct observation of the Sun at large solar zenith angles during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II)/Validation of International Satellites and study of Ozone Loss (VINTERSOL) campaign by several instruments provided a rich dataset for the retrieval and analysis of line-of-sight column composition, intercomparison, and measurement validation. A flexible, multi-species spectral fitting technique is presented and applied to spectral solar irradiance measurements made by the NCAR Direct beam Irradiance Atmospheric Spectrometer (DIAS) on-board the NASA DC-8. The approach allows for the independent retrieval of O₃, O₂·O₂, and aerosol optical properties, by constraining Rayleigh extinction. We examine the 19 January 2003 and 6 February 2003 flights and find very good agreement of O₃ and O₂·O₂ retrievals with forward-modeling calculations, even at large solar zenith angles, where refraction is important. Intercomparisons of retrieved ozone and aerosol optical thickness with results from the Ames Airborne Tracking Sunphotometer (AATS-14) are summarized.