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Pré-Publication, Document De Travail Année : 2010

The use of the high resolution visible in SAFNWC/MSG cloud mask

Marcel Derrien
  • Fonction : Auteur
Herve Le Gleau
  • Fonction : Auteur
  • PersonId : 870475
Marie-Paule Raoul
  • Fonction : Auteur

Résumé

NWCSAF (www.nwcsaf.org) consortium continuously develops and maintains a software package to extract various products from Meteosat Second Generation (MSG) imagery. Meteo-France has developed the part of this software package retrieving cloud mask and types, cloud top temperature and height. The improvement of the detection of small scale low clouds was a challenging task asked by the users of the SAFNWC/MSG cloud mask and type, for an earlier detection of convection and for a better screening of cloud-contaminated pixels prior the use of clear-sky radiances in the study of marine or land surface properties or their assimilation in Numerical Weather Prediction models. For this aim Meteo-France has developed an algorithm analysing the High Visible Resolution (HRV) of Spinning Enhanced Visible and Infrared Images (SEVIRI) and implemented it as an option in v2010 of the SAFNWC/MSG cloud mask available for users in June 2010. The paper describes the algorithm based on temporal analysis of HRV features and its application at the coarser spatial resolution of the SEVIRI cloud mask. Real examples illustrate situations where its behaviour can be visually estimated (improvements, misses and false alarms). Finally, the impact of its implementation is evaluated through a 11 month period by comparison with SYNOP and SHIP ground-based cloud covers. The increase of Cramer's coefficient (a normalized χ2 indicator) when using HRV denotes that it is better associated with the SYNOP and SHIP groundbased observations of the cloudiness categorized in three classes, clear(N≤2), broken (3≤N≤5) or cloudy (N≥6).
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Dates et versions

meteo-00604325 , version 1 (29-06-2011)

Identifiants

  • HAL Id : meteo-00604325 , version 1

Citer

Marcel Derrien, Herve Le Gleau, Marie-Paule Raoul. The use of the high resolution visible in SAFNWC/MSG cloud mask. 2010. ⟨meteo-00604325⟩

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