The ASSET intercomparison of ozone analyses: method and first results

• Main Authors: Geer, A. J., Lahoz, W. A., Bekki, Slimane, Bormann, N., Errera, Q., Eskes, H. J., Fonteyn, D., Jackson, D. R., Juckes, M. N., Massart, S., Peuch, V.-H., Rharmili, S., Segers, A.
• Other Authors: Data Assimilation Research Centre Reading (DARC), University of Reading (UOR), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), European Centre for Medium-Range Weather Forecasts (ECMWF), Belgian Institute for Space Aeronomy / Institut d'Aéronomie Spatiale de Belgique (BIRA-IASB), Royal Netherlands Meteorological Institute (KNMI), United Kingdom Met Office Exeter, British Atmospheric Data Centre, STFC Rutherford Appleton Laboratory (RAL), Science and Technology Facilities Council (STFC)-Science and Technology Facilities Council (STFC), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), CERFACS, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2006
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarctic; The Antarctic; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-00327911; https://hal.archives-ouvertes.fr/hal-00327911/document; https://hal.archives-ouvertes.fr/hal-00327911/file/acpd-6-4495-2006.pdf

International audience This paper examines 11 sets of ozone analyses from 7 different data assimilation systems. Two are numerical weather prediction (NWP) systems based on general circulation models (GCMs); the other five use chemistry transport models (CTMs). These systems contain either linearised or detailed ozone chemistry, or no chemistry at all. In most analyses, MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) ozone data are assimilated. Two examples assimilate SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) observations. The analyses are compared to independent ozone observations covering the troposphere, stratosphere and lower mesosphere during the period July to November 2003. Through most of the stratosphere (50 hPa to 1 hPa), biases are usually within ±10% and standard deviations less than 10% compared to ozonesondes and HALOE (Halogen Occultation Experiment). Biases and standard deviations are larger in the upper-troposphere/lower-stratosphere, in the troposphere, the mesosphere, and the Antarctic ozone hole region. In these regions, some analyses do substantially better than others, and this is mostly due to differences in the models. At the tropical tropopause, many analyses show positive biases and excessive structure in the ozone fields, likely due to known deficiencies in assimilated tropical wind fields and a degradation in MIPAS data at these levels. In the southern hemisphere ozone hole, only the analyses which correctly model heterogeneous ozone depletion are able to reproduce the near-complete ozone destruction over the pole. In the upper-stratosphere and mesosphere (above 5 hPa), some ozone photochemistry schemes caused large but easily remedied biases. The diurnal cycle of ozone in the mesosphere is not captured, except by the one system that includes a detailed treatment of mesospheric chemistry. In general, similarly good results are obtained no matter what the assimilation method (Kalman filter, three or four dimensional ...