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Potential use of surface-sensitive microwave observations over land in numerical weather prediction / E. Gerard in IEEE Transactions on geoscience and remote sensing, vol 49 n° 4 (April 2011)
[article]
Titre : Potential use of surface-sensitive microwave observations over land in numerical weather prediction Type de document : Article/Communication Auteurs : E. Gerard, Auteur ; Fatima Karbou, Auteur ; Florence Rabier, Auteur Année de publication : 2011 Article en page(s) : pp 1251 - 1262 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] assimilation des données
[Termes IGN] intégration de données
[Termes IGN] prévision météorologique
[Termes IGN] Special sensor microwave imager
[Termes IGN] télédétection en hyperfréquenceRésumé : (Auteur) This paper describes several sensitivity studies carried out with the French global 4-D-Var system to check its ability to assimilate surface-sensitive observations over land from the Special Sensor Microwave Imager (SSM/I). As well as a sound knowledge of land-surface parameters, the assimilation of SSM/I observations requires effective rain-detection and bias-correction algorithms. Three sensitivity components are hence analyzed with a special emphasis on the land-surface emissivity at SSM/I frequencies estimated from satellite observations. Several rain algorithms were tested to reject cloudy/rainy observations over land, and the bias-correction scheme was adapted to improve its performance over land and sea surfaces. Once these problems have been outlined, a global 4-D-Var assimilation experiment which assimilates SSM/I observations over land surfaces was run and compared with a control experiment. The impact on forecast scores has been found to be globally positive. Nevertheless, the very high sensitivity of SSM/I to each of the three components presented in this study is characterized by opposite effects that, once clustered together, lead to some residual biases over land due to their combined effects. Numéro de notice : A2011-132 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2010.2075936 Date de publication en ligne : 21/10/2010 En ligne : https://doi.org/10.1109/TGRS.2010.2075936 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30911
in IEEE Transactions on geoscience and remote sensing > vol 49 n° 4 (April 2011) . - pp 1251 - 1262[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 065-2011041 RAB Revue Centre de documentation En réserve L003 Disponible 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)
[article]
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'eauRésumé : (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
in Atmospheric Science Letters > vol 12 n° 1 (January - March 2011) . - pp 135 - 141[article]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 Better weather prediction using GPS: water vapor tomography in the Swiss Alps / Simon Lutz in GPS world, vol 21 n° 7 (July 2010)
[article]
Titre : Better weather prediction using GPS: water vapor tomography in the Swiss Alps Type de document : Article/Communication Auteurs : Simon Lutz, Auteur ; Donat Perler, Auteur ; Marc Troller, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 40 - 47 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] affaiblissement de la précision
[Termes IGN] Alpes centrales
[Termes IGN] atténuation du signal
[Termes IGN] humidité de l'air
[Termes IGN] prévision météorologique
[Termes IGN] Suisse
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] tomographie
[Termes IGN] traitement du signalRésumé : (Editeur) [...] Forecasting ability has improved as measurement technology, communications, and the understanding of atmospheric processes have improved. Meteorologists use measure- ments from various types of sensors and mathematical models to predict its future state. Yet better sampling of the current state of the atmosphere, particularly water vapor, is needed to produce more accurate and more timely forecasts. GPS can help. The signals from the GPS satellites must transit the atmosphere on their way to a receiver on the Earth's surface. The atmosphere's atoms and molecules slow down the signals so that they arrive slightly later than they would if the Earth was surrounded by a vacuum, and this effect shows up in the GPS receiver measurements. The receiver or measurement processing software needs to remove or model the effect to obtain accurate receiver positions. On the other hand, if all parameters affecting GPS measurements such as satellite and receiver coordinates are well known, then the delay imparted by the atmosphere can be estimated. It is possible to separate the effect of water vapor from that of the dry gases such as nitrogen, oxygen, and carbon dioxide and to provide a measure of the atmosphere's moisture content. Several national weather agencies are ingesting such estimates from networks of GPS receivers into experimental or operational numerical weather forecast models. But these values represent an integrated measure of moisture above a receiver. Profiles of how moisture is distributed with height would be more useful and might lead to better weather forecasts. In this month's column, a team of Swiss researchers discuss how they use data from a network of GPS receivers and the technique of tomography to obtain such profiles. Numéro de notice : A2010-271 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30465
in GPS world > vol 21 n° 7 (July 2010) . - pp 40 - 47[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 067-2010071 RAB Revue Centre de documentation En réserve L003 Disponible 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)
[article]
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 The 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)Permalinkvol 32 n° 2 - March - May 2009 - Storm surges around the globe: operational aspect (Bulletin de Marine geodesy) / R. LiPermalinkPermalinkPermalinkWeather Report : Meteorological applications of GNSS from space and on the ground / P. Poli in Inside GNSS, vol 3 n° 8 (November - December 2008)PermalinkAssessment of water budgets computed from NWP models and observational datasets during AMMA-EOP / Olivier Bock (2008)PermalinkThe EU-Cloudmap project: cirrus and contrail cloud-top maps from satellites for weather forecasting climate change analysis / J.P. Muller in International Journal of Remote Sensing IJRS, vol 28 n° 9 (May 2007)PermalinkInondations : les maires moins seuls / M. Mayo in Géomètre, n° 2033 (janvier 2007)PermalinkSimulation et assimilation de données radar pour la prévision de la convection profonde à fine échelle / Olivier Caumont (2007)Permalink