Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 5 1 2005 10.5194/acpd-5-847-2005 http://www.atmos-chem-phys-discuss.net/5/847/2005/ http://www.atmos-chem-phys-discuss.net/5/847/2005/acpd-5-847-2005.html http://www.atmos-chem-phys-discuss.net/5/847/2005/acpd-5-847-2005.pdf 847 862 2005-02-16 Shipborne solar absorption measurements of CO₂, CH₄, N₂O and CO and comparison with SCIAMACHY WFM-DOAS retrievals T. Warneke R. de Beek M. Buchwitz J. Notholt A. Schulz V. Velazco O. Schrems Institute of environmental physics, University of Bremen, Bremen, Germany Alfred Wegener Institute, Potsdam, Germany Alfred Wegener Institute, Bremerhaven, Germany CO, CH₄, N₂O and CO₂ were retrieved from high resolution solar absorption spectra obtained during a ship cruise from Capetown to Bremerhaven in January/February 2003 by Fourier Transform Infrared (FTIR) spectroscopy. Precisions of better than 0.5% for the column averaged volume mixing ratios (VMR) of CH₄ and CO₂ are achieved using of O₂ as a reference gas. Shipborne FTIR-measurements of CO and data from SCIAMACHY/ENVISAT retrieved by the Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS) retrieval algorithm show qualitatively the same latitudinal variations. WFM-DOAS data of CH₄, N₂O and CO₂ measured over sea exhibit a great spread. The spread is significantly reduced for satellite measurements over land and a reasonable agreement can be obtained if the shipborne data is compared with the closest SCIAMACHY measurements over land. The number of comparisons is too small to draw conclusions. However, by including only WFM-DOAS data with small errors the shipborne and WFM-DOAS data compare within 5% for CH₄ and CO₂ and within 30% for N₂O.