Articles | Volume 8, issue 16
Atmos. Chem. Phys., 8, 4759–4786, 2008

Special issue: Validation results for the Atmospheric Chemistry Experiment...

Atmos. Chem. Phys., 8, 4759–4786, 2008

  19 Aug 2008

19 Aug 2008

Validation of ACE-FTS N2O measurements

K. Strong1, M. A. Wolff1, T. E. Kerzenmacher1, K. A. Walker1,2, P. F. Bernath2,3, T. Blumenstock4, C. Boone2, V. Catoire5, M. Coffey6, M. De Mazière7, P. Demoulin8, P. Duchatelet8, E. Dupuy2, J. Hannigan6, M. Höpfner4, N. Glatthor4, D. W. T. Griffith9, J. J. Jin10, N. Jones9, K. Jucks11, H. Kuellmann12, J. Kuttippurath12,*, A. Lambert13, E. Mahieu8, J. C. McConnell10, J. Mellqvist14, S. Mikuteit4, D. P. Murtagh14, J. Notholt12, C. Piccolo15, P. Raspollini16, M. Ridolfi17, C. Robert5, M. Schneider4, O. Schrems18, K. Semeniuk10, C. Senten7, G. P. Stiller4, A. Strandberg14, J. Taylor1, C. Tétard19, M. Toohey1, J. Urban14, T. Warneke12, and S. Wood20 K. Strong et al.
  • 1Department of Physics, University of Toronto, Toronto, Ontario, Canada
  • 2Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada
  • 3Department of Chemistry, University of York, York, UK
  • 4Forschungszentrum Karlsruhe and University of Karlsruhe, Institute for Meteorology and Climate Research (IMK), Karlsruhe, Germany
  • 5Laboratoire de Physique et Chimie de L'Environment CNRS – Université d'Orléans, Orléans, France
  • 6National Center for Atmospheric Research, Boulder, CO, USA
  • 7Belgian Institute for Space Aeronomy, Brussels, Belgium
  • 8Institute of Astrophysics and Geophysics, University of Liège, Liège, Belgium
  • 9School of Chemistry, University of Wollongong, Wollongong, Australia
  • 10Department of Earth and Space Science and Engineering, York University, Toronto, Ontario, Canada
  • 11Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA
  • 12Institute for Environmental Physics, University of Bremen, Bremen, Germany
  • 13Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
  • 14Department of Radio and Space Science, Chalmers University of Technology, Gothenburg, Sweden
  • 15Department of Physics, University of Oxford, Oxford, UK
  • 16Institute of Applied Physics "Nello Carrara", National Research Center, Firenze, Italy
  • 17Dipartimento di Chimica Fisica e Inorganica, Università di Bologna, Bologna, Italy
  • 18Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
  • 19Laboratoire d'Optique Atmosphérique, Université des sciences et technologies de Lille, Villeneuve d'Ascq, France
  • 20National Institute of Water and Atmospheric Research Ltd., Lauder, New Zealand
  • *now at: LMD/CNRS Ecole Polytechnique, Palaiseau Cedex, France

Abstract. The Atmospheric Chemistry Experiment (ACE), also known as SCISAT, was launched on 12 August 2003, carrying two instruments that measure vertical profiles of atmospheric constituents using the solar occultation technique. One of these instruments, the ACE Fourier Transform Spectrometer (ACE-FTS), is measuring volume mixing ratio (VMR) profiles of nitrous oxide (N2O) from the upper troposphere to the lower mesosphere at a vertical resolution of about 3–4 km. In this study, the quality of the ACE-FTS version 2.2 N2O data is assessed through comparisons with coincident measurements made by other satellite, balloon-borne, aircraft, and ground-based instruments. These consist of vertical profile comparisons with the SMR, MLS, and MIPAS satellite instruments, multiple aircraft flights of ASUR, and single balloon flights of SPIRALE and FIRS-2, and partial column comparisons with a network of ground-based Fourier Transform InfraRed spectrometers (FTIRs). Between 6 and 30 km, the mean absolute differences for the satellite comparisons lie between −42 ppbv and +17 ppbv, with most within ±20 ppbv. This corresponds to relative deviations from the mean that are within ±15%, except for comparisons with MIPAS near 30 km, for which they are as large as 22.5%. Between 18 and 30 km, the mean absolute differences for the satellite comparisons are generally within ±10 ppbv. From 30 to 60 km, the mean absolute differences are within ±4 ppbv, and are mostly between −2 and +1 ppbv. Given the small N2O VMR in this region, the relative deviations from the mean are therefore large at these altitudes, with most suggesting a negative bias in the ACE-FTS data between 30 and 50 km. In the comparisons with the FTIRs, the mean relative differences between the ACE-FTS and FTIR partial columns (which cover a mean altitude range of 14 to 27 km) are within ±5.6% for eleven of the twelve contributing stations. This mean relative difference is negative at ten stations, suggesting a small negative bias in the ACE-FTS partial columns over the altitude regions compared. Excellent correlation (R=0.964) is observed between the ACE-FTS and FTIR partial columns, with a slope of 1.01 and an intercept of −0.20 on the line fitted to the data.

Final-revised paper