H. Bencherif

Publications (2)3.76 Total impact

• Article: An observed and analysed stratospheric ozone intrusion over the high Canadian Arctic UTLS region during the summer of 2003

  N. Semane, V.-H. Peuch, L. El Amraoui, H. Bencherif, S. Massart, D. Cariolle, J.-L. Attié, R. Abida
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  ABSTRACT: An exceptional ozone increase in the upper troposphere–lower stratosphere region has been recorded by an ozone sounding performed over the high Canadian Arctic at the beginning of August 2003. Simultaneously observed low humidity and low tropopause height suggest that this anomalous ozone enhancement is attributed to a downward transport from the stratosphere. This latter transport is investigated by using the Ertel potential vorticity field calculated from the ECMWF analyses. The occurrence of such high ozone concentrations is shown to be due to stratospheric ozone-rich air intrusions. These latter mesoscale phenomena are successfully captured using the assimilation of Envisat/MIPAS ozone profiles into the global three-dimensional chemistry transport model of Météo-France (MOCAGE). This study shows that Envisat/MIPAS ozone profiles assimilation adds value in the sense that the analyses capture the whole stratospheric intrusion episode, whereas the raw model simulation does not. Copyright © 2007 Royal Meteorological Society
  Quarterly Journal of the Royal Meteorological Society 11/2007; 133(S2):171 - 178. · 2.91 Impact Factor
• Article: Examination of the 2002 major warming in the southern hemisphere using ground-based and Odin/SMR assimilated data: stratospheric ozone distributions and tropic/mid-latitude exchange

  H Bencherif, L E. Amraoui, N Semane, S Massart, D V.i.d.y.a.r.a.n.y.a. Charyulu, A Hauchecorne, V H. Peuch
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  ABSTRACT: Following an exceptionally active winter, the 2002 Southern Hemisphere (SH) major warming occurred in late September. It was preceded by three minor warming events that occurred in late August and early September, and yielded vortex split and break-down over Antarctica. Ozone (O3 and nitrous oxide (N2O) profiles obtained during that period of time (15 August - 4 October) by the Sub-Millimetre Radiometer (SMR) aboard the Odin satellite are assimilated into MOCAGE (Modélisation Isentrope du transport Mésoéchelle de l'Ozone Stratosphérique par Advection), a global three-dimensional chemistry transport model of Météo-France. The assimilated algorithm is a three-dimensional-FGAT built by the European Centre for Research and Advance Training in Scientific Computation (CERFACS) using the PALM (Projet d'Assimilation par Logiciel Multi-méthode) software. The assimilated O3 and N2O profiles and isentropic distributions are compared to ground-based measurements (LIDAR and balloon-sonde) and to maps of advected potential vorticity (APV). The latter is computed by the MIMOSA (Modélisation Isentrope du transport Mésoéchelle de l'Ozone Stratosphérique par Advection) model, a high-resolution advection transport model, using meteorological fields from the European Centre for Medium-Range Weather Forecasts (ECMWF). It is found that O3 concentrations retrieved by the MOCAGE-PALM assimilation system show a reasonably good agreement in the 20-28 km height range when compared with ground-based profiles. This altitude range corresponds to the intersection between the MOCAGE levels (0-28 km) and SMR O3 retrievals (20-50 km). Moreover, comparison of N2O assimilated fields with MIMOSA APV maps indicates that the dramatic split and subsequent break-down of the polar vortex, as well as the associated mixing of mid- and low-latitude stratospheric air, are well resolved and pictured by MOCAGE-PALM. The present study demonstrates also that the tremendous dynamics and associated polar vortex deformations during the 2002-austral-winter have modified ozone and nitrous oxide distributions not only at the vicinity of the polar vortex, but over topics and subtropics as well.PACS Nos.: 92.60.H-, 92.60.Hd, 92.70.Cp, 92.70.GtAprès un hiver exceptionnellement actif, le réchauffement majeur dans l'hémisphère sud (SH) de 2002 s'est produit fin septembre. Il a été précédé de trois réchauffements mineurs fin août et début septembre et il a causé une séparation et une dislocation du vortex au dessus de l'Antartique. Les profils d'ozone (O3) et de protoxyde d'azote (NO2) obtenus pendant cette période (15 août - 4 octobre) à partir de l'expérience SMR (Sub-Millimetre Radiometer) à bord du satellite Odin sont assimilés par MOCAGE Mocage (Modélisation isentrope du transport mésoéchelle de l'ozone stratosphérique par advection), modèle tri-dimensionnel de transport et chimie de Météo-France. L'algorithme est un tri-dimensionnel-FGAT développé par le Centre Européen de Recherche en Formation Avancée de Calculs Scientifiques (CERFACS) qui utilise le logiciel PALM (Projet d'assimilation par logiciel multi-méthode). Les profils et les distributions isentropes assimilés de O3 et de N2O sont comparées à des mesures prises du sol (par LIDAR et par ballon-sonde) et à des cartes de vorticité potentielle advectée (APV). Ces dernières sont calculées par le modèle MIMOSA, un modèle de transport par advection de haute résolution qui utilise les champs météorologiques du European Center for Medium-Range Weather Forecast (ECMWF). Nous trouvons que les concentrations de O3 assimilées par MOCAGE-PALM sont en bon accord dans le domaine 20-28 km avec les profils obtenus du sol.
  Canadian Journal of Physics 10/2007; 85(11):1287-1300. · 0.86 Impact Factor