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Auteur Philippe Collard |
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Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externesWest African Monsoon observed with ground-based GPS receivers during African Monsoon Multidisciplinary Analysis (AMMA) / Olivier Bock in Journal of geophysical research : Atmospheres, vol 113 n° D21 (16 November 2008)
Titre : West African Monsoon observed with ground-based GPS receivers during African Monsoon Multidisciplinary Analysis (AMMA) Type de document : Article/Communication Auteurs : Olivier Bock Année de publication : 2008 Projets : AMMA & AMMA-2 / Janicot, Serge Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] circulation atmosphérique
[Termes IGN] données GPS
[Termes IGN] erreur systématique
[Termes IGN] humidité de l'air
[Termes IGN] modèle de simulation
[Termes IGN] mousson
[Termes IGN] phénomène atmosphérique
[Termes IGN] précipitation
[Termes IGN] vapeur d'eau
[Termes IGN] variation saisonnièreRésumé : (auteur) A ground-based GPS network has been established over West Africa in the framework of African Monsoon Multidisciplinary Analysis (AMMA) in tight cooperation between French and African institutes. The experimental setup is described and preliminary highlights are given for different applications using these data. Precipitable water vapor (PWV) estimates from GPS are used for evaluating numerical weather prediction (NWP) models and radiosonde humidity data. Systematic tendency errors in model forecasts are evidenced. Correlated biases in NWP model analyses and radiosonde data are evidenced also, which emphasize the importance of radiosonde humidity data in this region. PWV and precipitation are tightly correlated at seasonal and intraseasonal timescales. Almost no precipitation occurs when PWV is smaller than 30 kg m−2. This limit in PWV also coincides well with the location of the intertropical discontinuity. Five distinct phases in the monsoon season are determined from the GPS PWV, which correspond either to transition or stationary periods of the West African Monsoon system. They may serve as a basis for characterizing interannual variability. Significant oscillations in PWV are observed with 10- to 15-day and 15- to 20-day periods, which suggest a strong impact of atmospheric circulation on moisture and precipitation. The presence of a diurnal cycle oscillation in PWV with marked seasonal evolutions is found. This oscillation involves namely different phasing of moisture fluxes in different layers implying the low-level jet, the return flow, and the African Easterly Jet. The broad range of timescales observed with the GPS systems shows a high potential for investigating many atmospheric processes of the West African Monsoon. Numéro de notice : A2008-656 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2008JD010327 Date de publication en ligne : 05/11/2008 En ligne : https://doi.org/10.1029/2008JD010327 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98266
in Journal of geophysical research : Atmospheres > vol 113 n° D21 (16 November 2008)[article]
