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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys. Discuss., 8, 4499-4559, 2008
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04 Mar 2008
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). A final paper in ACP is not foreseen.
Validation of water vapour profiles from the Atmospheric Chemistry Experiment (ACE)
M. R. Carleer1, C. D. Boone2, K. A. Walker2,3, P. F. Bernath2,4, K. Strong3, R. J. Sica5, C. E. Randall6, H. Vömel7, J. Kar3, M. Höpfner8, M. Milz8,*, T. von Clarmann8, R. Kivi9, J. Valverde-Canossa10, C. E. Sioris11, M. R. M. Izawa12, E. Dupuy2, C. T. McElroy3,11, J. R. Drummond3,13, C. R. Nowlan3, J. Zou3, F. Nichitiu3, S. Lossow14, J. Urban15, D. Murtagh15, and D. G. Dufour16
1Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, Belgium
2Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada
3Department of Physics, University of Toronto, Toronto, Ontario, Canada
4Department of Chemistry, University of York, UK
5Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada
6Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
7Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
8Forschungszentrum Karlsruhe and Universität Karlsruhe, Institut für Meteorologie und Klimaforschung, Karlsruhe, Germany
9Finnish Meteorological Institute, Arctic Research Center, Sodankylä, Finland
10Universidad Nacional, Heredia, Costa Rica
11Environment Canada, Downsview, Ontario, Canada
12Department of Earth Sciences, University of Western Ontario, London, Ontario, Canada
13Department of Physics & Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
14Department of Meteorology, Stockholm University, Stockholm, Sweden
15Department of Radio and Space Science, Chalmers University of Technology, Göteborg, Sweden
16Picomole Instruments Inc., Edmonton, Alberta, Canada
*now at: Institutionen för Rymdvetenskap, Luleå Tekniska Universitet, Kiruna, Sweden

Abstract. The Atmospheric Chemistry Experiment (ACE) mission was launched in August 2003 to sound the atmosphere by solar occultation. Water vapour (H2O), one of the most important molecules for climate and atmospheric chemistry, is one of the key species provided by the two principal instruments, the infrared Fourier Transform Spectrometer (ACE-FTS) and the MAESTRO UV-Visible spectrometer (ACE-MAESTRO). The first instrument performs measurements on several lines in the 1362–2137 cm−1 range, from which vertically resolved H2O concentration profiles are retrieved, from 7 to 90 km altitude. ACE-MAESTRO measures profiles using the water absorption band in the near infrared part of the spectrum at 926.0–969.7 nm. This paper presents a comprehensive validation of the ACE-FTS profiles. We have compared the H2O volume mixing ratio profiles with space-borne (SAGE II, HALOE, POAM III, MIPAS, SMR) observations and measurements from balloon-borne frostpoint hygrometers and a ground based lidar. We show that the ACE-FTS measurements provide H2O profiles with small retrieval uncertainties in the stratosphere (better than 5% from 15 to 70 km, gradually increasing above). The situation is unclear in the upper troposphere, due mainly to the high variability of the water vapour volume mixing ratio in this region. A new water vapour data product from the ACE-MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) is also presented and initial comparisons with ACE-FTS are discussed.

Citation: Carleer, M. R., Boone, C. D., Walker, K. A., Bernath, P. F., Strong, K., Sica, R. J., Randall, C. E., Vömel, H., Kar, J., Höpfner, M., Milz, M., von Clarmann, T., Kivi, R., Valverde-Canossa, J., Sioris, C. E., Izawa, M. R. M., Dupuy, E., McElroy, C. T., Drummond, J. R., Nowlan, C. R., Zou, J., Nichitiu, F., Lossow, S., Urban, J., Murtagh, D., and Dufour, D. G.: Validation of water vapour profiles from the Atmospheric Chemistry Experiment (ACE), Atmos. Chem. Phys. Discuss., 8, 4499-4559, doi:10.5194/acpd-8-4499-2008, 2008.
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