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Frequency of extreme Sahelian storms tripled since 1982 in satellite observations / Christopher M. Taylor in Nature letters, vol 544 n° 7651 (27 April 2017)  

Public [article]  inNature letters > vol 544 n° 7651 (27 April 2017) . - pp 475 - 478 Titre : Frequency of extreme Sahelian storms tripled since 1982 in satellite observations Type de document : Article/Communication Auteurs : Christopher M. Taylor, Auteur ; Danijel Belušić, Auteur ; Françoise Guichard, Auteur ; Douglas J. Parker, Auteur ; Théo Vischel, Auteur ; Olivier Bock , Auteur ; Phil P. Harris, Auteur ; Serge Janicot, Auteur ; Cornelia Klein, Auteur ; Gérémy Panthou, Auteur Année de publication : 2017 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp 475 - 478 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse diachronique [Termes IGN] changement climatique [Termes IGN] convection [Termes IGN] données météorologiques [Termes IGN] pluie [Termes IGN] Sahara, désert du [Termes IGN] Sahel [Termes IGN] température [Termes IGN] tempête Résumé : (auteur) The hydrological cycle is expected to intensify under global warming, with studies reporting more frequent extreme rain events in many regions of the world, and predicting increases in future flood frequency. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective rainfall. A globally important group of intense storms—mesoscale convective systems (MCSs)—poses a particular challenge, because they organize dynamically on spatial scales that cannot be resolved by conventional climate models. Here, we use 35 years of satellite observations from the West African Sahel to reveal a persistent increase in the frequency of the most intense MCSs. Sahelian storms are some of the most powerful on the planet, and rain gauges in this region have recorded a rise in ‘extreme’ daily rainfall totals. We find that intense MCS frequency is only weakly related to the multidecadal recovery of Sahel annual rainfall, but is highly correlated with global land temperatures. Analysis of trends across Africa reveals that MCS intensification is limited to a narrow band south of the Sahara desert. During this period, wet-season Sahelian temperatures have not risen, ruling out the possibility that rainfall has intensified in response to locally warmer conditions. On the other hand, the meridional temperature gradient spanning the Sahel has increased in recent decades, consistent with anthropogenic forcing driving enhanced Saharan warming. We argue that Saharan warming intensifies convection within Sahelian MCSs through increased wind shear and changes to the Saharan air layer. The meridional gradient is projected to strengthen throughout the twenty-first century, suggesting that the Sahel will experience particularly marked increases in extreme rain. The remarkably rapid intensification of Sahelian MCSs since the 1980s sheds new light on the response of organized tropical convection to global warming, and challenges conventional projections made by general circulation models. Numéro de notice : A2017-859 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1038/nature22069 Date de publication en ligne : 26/04/2017 En ligne : http://doi.org/10.1038/nature22069 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89838 [article]

Operational meteorology in West Africa : observational networks, weather analysis and forecasting / Andreas H. Fink in Atmospheric Science Letters, vol 12 n° 1 (January - March 2011)  

Public [article]  inAtmospheric Science Letters > vol 12 n° 1 (January - March 2011) . - pp 135 - 141 Titre : Operational meteorology in West Africa : observational networks, weather analysis and forecasting Type de document : Article/Communication Auteurs : Andreas H. Fink, Auteur ; Anna Agustí‐Panareda, Auteur ; Douglas J. Parker, Auteur ; Jean-Philippe Lafore, Auteur ; Jean-Blaise Ngamini, Auteur ; Ernest Afiesimama, Auteur ; Anton Beljaars, Auteur ; Olivier Bock , Auteur ; Michael Christoph, Auteur ; Francis Didé, Auteur ; et al., Auteur Année de publication : 2011 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp 135 - 141 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] Afrique occidentale [Termes IGN] coordonnées GPS [Termes IGN] données météorologiques [Termes IGN] modèle météorologique [Termes IGN] mousson [Termes IGN] prévision météorologique [Termes IGN] radiosondage [Termes IGN] teneur intégrée en vapeur d'eau Résumé : (Auteur) Real‐time surface and upper‐air observations are crucial to the analysis and forecasting of the West African monsoon (WAM). This paper will focus on the African Monsoon—Multidisciplinary Analyses (AMMA)‐driven reactivation and modernisation of the radiosonde network over West Africa, its potential long‐term impact on upper‐air operations in the region, the influence of the additional data in WAM analyses and forecasting, and the AMMA‐related development and usage of the West African Analysis/Forecasting (WASA/F) forecast method. Numéro de notice : A2011-594 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/asl.324 Date de publication en ligne : 22/02/2011 En ligne : https://doi.org/10.1002/asl.324 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91518 [article]

The AMMA field campaigns : accomplishments and lessons learned / Thierry Lebel in Atmospheric Science Letters, vol 12 n° 1 (January - March 2011)  

Public [article]  inAtmospheric Science Letters > vol 12 n° 1 (January - March 2011) . - pp 123 - 128 Titre : The AMMA field campaigns : accomplishments and lessons learned Type de document : Article/Communication Auteurs : Thierry Lebel, Auteur ; Douglas J. Parker, Auteur ; Cyrille Flamant, Auteur ; Hartmut Höller, Auteur ; Jan Polcher, Auteur ; Jean-Luc Redelsperger, Auteur ; Chris Thorncroft, Auteur ; Olivier Bock , Auteur ; Bernard Bourles, Auteur ; Sylvie Galle, Auteur ; Béatrice Marticorena, Auteur ; et al., Auteur Année de publication : 2011 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp 123 - 128 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] aérostat [Termes IGN] Afrique occidentale [Termes IGN] campagne d'expérimentation [Termes IGN] coopération technique [Termes IGN] lidar atmosphérique [Termes IGN] mousson [Termes IGN] photomètre [Termes IGN] radar Résumé : (Auteur) The AMMA (African Monsoon Multidiscplinary Analysis) field programme aimed at documenting the West African Monsoon (WAM) climate system, in all its geophysical components. It also includes an important socio‐economic component. Encompassing a wide range of spatial and time scales, AMMA is one of the most ambitious such programmes ever set up. While the key accomplishments of AMMA are summarised in this paper, a few lessons of broad interest are also drawn both as a tribute to the extraordinary efforts made by a community of several hundreds of people and as possible guidelines for ensuring a long lasting future to integrated climate and environmental studies in West Africa. Copyright © 2011 Royal Meteorological Society Numéro de notice : A2011-592 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/asl.323 Date de publication en ligne : 22/02/2011 En ligne : https://doi.org/10.1002/asl.323 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91515 [article]