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The AMMA field campaigns : accomplishments and lessons learned / Thierry Lebel in Atmospheric Science Letters, vol 12 n° 1 (January - March 2011)
[article]
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] radarRésumé : (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
in Atmospheric Science Letters > vol 12 n° 1 (January - March 2011) . - pp 123 - 128[article]The large‐scale water cycle of the West African monsoon / Olivier Bock in Atmospheric Science Letters, vol 12 n° 1 (January - March 2011)
[article]
Titre : The large‐scale water cycle of the West African monsoon Type de document : Article/Communication Auteurs : Olivier Bock , Auteur ; Françoise Guichard, Auteur ; Rémi Meynadier, Auteur ; Sébastien Gervois, Auteur ; Anna Agustí‐Panareda, Auteur ; Anton Beljaars, Auteur ; Aaron Boone, Auteur ; Mathieu Nuret, Auteur ; Jean-Luc Redelsperger, Auteur ; Pascal Roucou, Auteur Année de publication : 2011 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp 51 - 57 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] analyse comparative
[Termes IGN] analyse diachronique
[Termes IGN] bilan hydrique
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] modèle météorologique
[Termes IGN] mousson
[Termes IGN] vapeur d'eau
[Termes IGN] variation saisonnièreRésumé : (Auteur) The vertically integrated water budget of West Africa is investigated with a hybrid dataset based on observational and modelling products elaborated by the African Monsoon Multidisciplinary Analyses (AMMA) and with several numerical weather prediction (NWP) products including the European Centre for Medium‐Range Weather Forecasts (ECMWF) AMMA reanalysis. Seasonal and intraseasonal variations are quantified over the period 2002–2007. Links between the budget terms are analyzed regionally, from the Guinean coast to the Sahel zone. Water budgets from the NWP systems are intercompared and evaluated against the hybrid dataset. Large deficiencies are evidenced in all the NWP products. Hypotheses are proposed about their origins and several improvements are foreseen. Copyright © 2010 Royal Meteorological Society. Numéro de notice : A2011-593 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/asl.288 Date de publication en ligne : 16/08/2010 En ligne : https://doi.org/10.1002/asl.288 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91516
in Atmospheric Science Letters > vol 12 n° 1 (January - March 2011) . - pp 51 - 57[article]West African Monsoon water cycle: 1. A hybrid water budget data set / Rémi Meynadier in Journal of geophysical research : Atmospheres, vol 115 n° D19 (2010)
[article]
Titre : West African Monsoon water cycle: 1. A hybrid water budget data set Type de document : Article/Communication Auteurs : Rémi Meynadier, Auteur ; Olivier Bock , Auteur ; Françoise Guichard, Auteur ; Aaron Boone, Auteur ; Pascal Roucou, Auteur ; Jean-Luc Redelsperger, Auteur Année de publication : 2010 Article en page(s) : 21 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] bilan hydrique
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] évapotranspiration
[Termes IGN] mousson
[Termes IGN] précipitation
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] variation saisonnièreRésumé : (auteur) This study investigates the West African Monsoon water cycle with the help of a new hybrid water budget data set developed within the framework of the African Monsoon Multidisciplinary Analyses. Surface water and energy fluxes are estimated from an ensemble of land surface model simulations forced with elaborate precipitation and radiation products derived from satellite observations, while precipitable water tendencies are estimated from numerical weather prediction analyses. Vertically integrated atmospheric moisture flux convergence is estimated as a residual. This approach provides an advanced, comprehensive atmospheric water budget, including evapotranspiration, rainfall, and atmospheric moisture flux convergence, together with other surface fluxes such as runoff and net radiation. The annual mean and the seasonal cycle of the atmospheric water budget are presented and the couplings between budget terms are discussed for three climatologically distinct latitudinal bands between 6°N and 20°N. West Africa is shown to be alternatively a net source and sink region of atmospheric moisture, depending on the season (a source during the dry season and a sink during the wet season). Several limiting and controlling factors of the regional water cycle are highlighted, suggesting strong sensitivity to atmospheric dynamics and surface radiation. Some insight is also given into the underlying smaller‐scale processes. The relationship between evapotranspiration and precipitation is shown to be very different between the Sahel and the regions more to the south and partly controlled by net surface radiation. Strong correlations are found between precipitation and moisture flux convergence over the whole region from daily to interannual time scales. Causality is also established between monthly mean anomalies. Hence, precipitation anomalies are preceded by moisture flux convergence anomalies and followed by moisture flux divergence and evapotranspiration anomalies. The results are discussed in comparison to other studies. Numéro de notice : A2010-653 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2010JD013917 Date de publication en ligne : 01/10/2010 En ligne : https://doi.org/10.1029/2010JD013917 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91724
in Journal of geophysical research : Atmospheres > vol 115 n° D19 (2010) . - 21 p.[article]Voir aussiDocuments numériques
en open access
West African Monsoon water cycle 1 - pdf éditeurAdobe Acrobat PDF West African Monsoon water cycle: 2. Assessment of numerical weather prediction water budgets / Rémi Meynadier in Journal of geophysical research : Atmospheres, vol 115 n° D19 (2010)
[article]
Titre : West African Monsoon water cycle: 2. Assessment of numerical weather prediction water budgets Type de document : Article/Communication Auteurs : Rémi Meynadier, Auteur ; Olivier Bock , Auteur ; Sébastien Gervois, Auteur ; Françoise Guichard, Auteur ; Jean-Luc Redelsperger, Auteur ; Anna Agustí‐Panareda, Auteur ; Anton Beljaars, Auteur Année de publication : 2010 Article en page(s) : 24 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] circulation atmosphérique
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] évapotranspiration
[Termes IGN] mousson
[Termes IGN] prévision météorologiqueRésumé : (auteur) Water budgets from European Centre for Medium‐Range Weather Forecasts (ECMWF) Re‐Analysis (ERA)‐Interim and National Centers for Environmental Prediction (NCEP) Reanalysis I and II are intercompared and compared to GPS precipitable water and to the 6 year hybrid budget data set described in part 1 of this study. Deficiencies are evidenced in the reanalyses which are most pronounced over the Sahel. Results from operational models (ECMWF Integrated Forecast System, NCEP Global Forecast System, and ARPEGE‐Tropiques) and the special ECMWF African Monsoon Multidisciplinary Analyses reanalysis confirm and help understanding these findings. A bias (∼1–2 mm d−1) in precipitation and evapotranspiration leads to an unrealistic view of West Africa as a moisture source during the summer. North of the rainband (13°N–16°N), moisture flux convergence (MFC) shows a minimum in the NCEP models and divergence in the ECMWF models not consistent with the hybrid data set. This feature, added to presence of a deep layer of northerly dry air advected at midlevels (800–400 hPa), is thought to block the development of deep convection in the models and the northward propagation of the monsoonal rainband. The northerly flow is part of a shallow meridional circulation that is driven by the Saharan heat low. This circulation appears too strong in some of the models, a possible consequence of the too‐approximate representation of physical processes and land surface properties over the Sahel. In most of the models, evapotranspiration shows poor connection with precipitation. This is linked with large analysis increments in precipitable water, soil moisture, and MFC. Despite the large biases affecting the water budget components in the models, temporal variations (seasonal and interannual) might nevertheless be recovered with reasonable accuracy. Numéro de notice : A2010-654 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2010JD013919 En ligne : https://doi.org/10.1029/2010JD013919 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91725
in Journal of geophysical research : Atmospheres > vol 115 n° D19 (2010) . - 24 p.[article]Voir aussiDocuments numériques
en open access
West African Monsoon water cycle 2 - pdf éditeurAdobe Acrobat PDF Global 4DVAR assimilation and forecast experiments using AMSU observations over land. Part II: Impacts of assimilating surface-sensitive channels on the African monsoon during AMMA / Fatima Karbou in Weather and Forecasting, vol 25 n° 1 (February 2010)
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Titre : Global 4DVAR assimilation and forecast experiments using AMSU observations over land. Part II: Impacts of assimilating surface-sensitive channels on the African monsoon during AMMA Type de document : Article/Communication Auteurs : Fatima Karbou, Auteur ; Florence Rabier, Auteur ; Jean-Philippe Lafore, Auteur ; Jean-Luc Redelsperger, Auteur ; Olivier Bock , Auteur Année de publication : 2010 Projets : AMMA & AMMA-2 / Janicot, Serge Article en page(s) : pp Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Afrique occidentale
[Termes IGN] assimilation des données
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] emissivité
[Termes IGN] étude de faisabilité
[Termes IGN] humidité de l'air
[Termes IGN] image NOAA-AMSU
[Termes IGN] mousson
[Termes IGN] prévision météorologiqueRésumé : (auteur) Observations from Advanced Microwave Sounding Unit-A and -B (AMSU-A and -B) have been more intensively used over sea than over land because of large uncertainties about the land surface emissivity and the skin temperature. Several methods based on a direct estimation of the land emissivity from satellite observations have been found to be very useful for improving the assimilation of sounding channels over land. Feasibility studies have been conducted within the Météo-France global assimilation system in order to examine the possibility of assimilating low-level atmospheric observations receiving a contribution from the land surface. The present study reports on three 2-month assimilation and forecast experiments, which include the assimilation of surface-sensitive observations from AMSU-A and -B together with a control experiment, which represents the operational model. The assimilation experiments have been compared with the control, and important changes in the analyzed atmospheric fields and in the precipitation forecasts over parts of the tropics, and especially over West Africa, have been noticed. The experiments seem to emphasize the atmospheric moistening in India, South America, and in West Africa, together with atmospheric drying over Saudi Arabia and northeast Africa. The drying or moistening of the atmosphere has been successfully evaluated using independent measurements from the GPS African Monsoon Multidisciplinary Analysis (AMMA) network. Precipitation and OLR forecasts have also been examined and compared with independent measurements. Physically, the changes result in a better-organized African monsoon with a stronger ITCZ in terms of ascent, vorticity, and precipitation, but there is no northward shift of the monsoon system. Low-level humidity observations have been found to have important impacts on the analysis and to produce positive impacts on forecast scores over the tropics. Numéro de notice : A2010-664 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1175/2009WAF2222244.1 Date de publication en ligne : 01/02/2010 En ligne : https://doi.org/10.1175/2009WAF2222244.1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91770
in Weather and Forecasting > vol 25 n° 1 (February 2010) . - pp[article]Documents numériques
en open access
Global 4DVAR assimilation and forecast experiments ... - pdf éditeurAdobe Acrobat PDF Diurnal cycle of the intertropical discontinuity over West Africa analysed by remote sensing and mesoscale modelling / Bernhard Pospichal in Quarterly Journal of the Royal Meteorological Society, vol 136 n° S1 (January 2010)PermalinkMéthodologie GPS, mesure des déformations verticales et humidité atmosphérique / Marie-Noëlle Bouin (2010)PermalinkThe GHYRAF (Gravity and Hydrology in Africa) experiment: Description and first results / Jacques Hinderer in Journal of geodynamics, vol 48 n° 3-5 (December 2009)PermalinkThe impacts of AMMA radiosonde data on the French global assimilation and forecast system / C. Faccani in Weather and Forecasting, vol 24 n° 5 (October 2009)PermalinkVerification of NWP model analyses and radiosonde humidity data with GPS precipitable water vapor estimates during AMMA / Olivier Bock in Weather and Forecasting, vol 24 n° 4 (August 2009)PermalinkOn the late northward propagation of the West African monsoon in summer 2006 in the region of Niger/Mali / Philippe Drobinski in Journal of geophysical research : Atmospheres, vol 114 n° D9 (2009)PermalinkRadiosonde humidity bias correction over the West African region for the special AMMA reanalysis at ECMWF / Anna Agustí‐Panareda in Quarterly Journal of the Royal Meteorological Society, vol 135 n° 640 (April 2009 part A)PermalinkMission AMMA : L'apport de l'IGN / Olivier Bock in IGN magazine, n° 51 (janvier - février 2009)PermalinkWest 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)PermalinkCorrection of humidity bias for Vaïsala RS80 sondes during AMMA 2006 Observing Period / Mathieu Nuret in Journal of Atmospheric and Oceanic Technology, vol 25 n° 11 (November 2008)Permalink