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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 Absolute seafloor vertical positioning using combined pressure gauge and kinematic GPS data / Valérie Ballu in Journal of geodesy, vol 84 n° 1 (January 2010)
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Titre : Absolute seafloor vertical positioning using combined pressure gauge and kinematic GPS data Type de document : Article/Communication Auteurs : Valérie Ballu, Auteur ; Marie-Noëlle Bouin , Auteur ; Stéphane Calmant, Auteur ; et al., Auteur Année de publication : 2010 Article en page(s) : pp 65 - 77 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] coordonnées GPS
[Termes IGN] données marégraphiques
[Termes IGN] fond marin
[Termes IGN] GPS en mode cinématique
[Termes IGN] Pacifique (océan)
[Termes IGN] positionnement absolu
[Termes IGN] profondeur
[Termes IGN] séisme
[Termes IGN] subduction
[Termes IGN] tectonique des plaques
[Termes IGN] VanuatuRésumé : (Auteur) Knowledge of the position and motion of points on the seafloor can be critically important in both fundamental research (for example, global geodesy and plate tectonics) and for more practical applications such as seismic risk evaluation, off-shore construction and pipeline monitoring. In the Vanuatu subduction zone, for example, measuring deformation underwater could provide valuable information for modeling deformation and understanding the seismic cycle. We report a shallow water experiment in Vanuatu to measure the relative and absolute depth of seafloor points. The experiment differs from previous efforts mainly in that it uses the height of the sea surface determined by kinematic GPS, allowing us to locate the points in a global reference frame. The ITRF2005 ellipsoidal height of a seafloor benchmark was determined with a 1-sigma uncertainty of 0.7–2.1 cm. The estimated ellipsoidal height differs only by a few tenths of a centimeter between measurements made in 2004 and another set made in 2006. These results are encouraging and open new perspectives for vertical underwater deformation monitoring in shallow water areas. Sea-surface GPS measurements can also help to reduce the uncertainty in depth difference determination for relative measurements. Copyright Springer Numéro de notice : A2010-034 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-009-0345-y Date de publication en ligne : 19/09/2009 En ligne : https://doi.org/10.1007/s00190-009-0345-y Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30230
in Journal of geodesy > vol 84 n° 1 (January 2010) . - pp 65 - 77[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2010011 SL Revue Centre de documentation Revues en salle Disponible Isostatic stability of the East Antarctic station Dumont d'Urville from long-term geodetic observations and geophysical models / Martine Amalvict in Polar research, vol 28 n° 2 (August 2009)
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Titre : Isostatic stability of the East Antarctic station Dumont d'Urville from long-term geodetic observations and geophysical models Type de document : Article/Communication Auteurs : Martine Amalvict, Auteur ; Pascal Willis , Auteur ; Guy Wöppelmann , Auteur ; Eric Ivins, Auteur ; Marie-Noëlle Bouin , Auteur ; Laurent Testut, Auteur ; Jacques Hinderer, Auteur Année de publication : 2009 Article en page(s) : pp 193 - 202 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Antarctique
[Termes IGN] coordonnées GPS
[Termes IGN] déformation verticale de la croute terrestre
[Termes IGN] données géophysiques
[Termes IGN] rebond post-glaciaireRésumé : (auteur) Geodetic measurements of the vertical crustal displacement collocated with absolute gravity changes provide a discriminatory measurement of present-day glacial changes, versus more deeply seated rock motions caused by glacial isostatic adjustment (GIA). At the East Antarctic station of Dumont d'Urville, we compare the displacements derived from continuous DORIS (1993.0–2006.0) and Global Positioning System (GPS) (1999.0–2005.7) data, and observed changes in absolute gravity (2000–2006), with the predicted vertical displacement and change in gravity from GIA modelling. The geodetic results have mutual self-consistency, suggest station stability and provide upper bounds on both GIA and secular ice mass changes. The GIA models tend to predict amplitudes of rock motion larger than those observed, and we conclude that this part of Antarctica is probably experiencing a slight gain in ice mass, in contrast to West Antarctica. Numéro de notice : A2009-579 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article DOI : 10.1111/j.1751-8369.2008.00091.x En ligne : http://doi.org/10.1111/j.1751-8369.2008.00091.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88648
in Polar research > vol 28 n° 2 (August 2009) . - pp 193 - 202[article]Water vapour variability induced by urban/rural surface heterogeneities during convective conditions / Cédric Champollion in Quarterly Journal of the Royal Meteorological Society, vol 135 n° 642 (July 2009 Part A)
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Titre : Water vapour variability induced by urban/rural surface heterogeneities during convective conditions Type de document : Article/Communication Auteurs : Cédric Champollion, Auteur ; Philippe Drobinski, Auteur ; M. Haeffelin, Auteur ; Olivier Bock , Auteur ; Jérôme Tarniewicz , Auteur ; Marie-Noëlle Bouin , Auteur ; R. Vautard, Auteur Année de publication : 2009 Projets : 3-projet - voir note / Janicot, Serge Article en page(s) : pp 1266 - 1276 Note générale : bibliographie
This research has been funded by the Centre National de la Recherche Scientifique (CNRS), the Direction Générale de l’Armement (DGA) and the Ecole Polytechnique as well as the Institut des Sciences de l’Univers (INSU) through the Programme Atmosphère Ocean à Multiéchelle (PATOM) and Programme National de Télédétection Spatiale (PNTS)Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] coordonnées GPS
[Termes IGN] météorologie locale
[Termes IGN] Paris (75)
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] teneur intégrée en vapeur d'eau
[Termes IGN] zone urbaineRésumé : (auteur) Scientific interest in urban meteorology has increased because highly populated areas experience high vulnerability to pollution or heavy rain. However, compared to urban air quality or urban heat island (UHI) processes, the urban water vapour cycle is poorly understood because it has been investigated less due to the lack of upper‐air measurements and the high sensitivity of surface measurements to local heterogeneities. In this paper, surface measurements of wind, temperature, pressure and humidity, as well as integrated water vapour (IWV) from GPS and MODIS and numerical simulations, have been used to investigate the urban cycle of water vapour in May and June 2004 during the VAPIC field experiment in the Paris area.
The surface data show the typical characteristics of an urban area with the absence of water vapour sources and a UHI of about 6 °C at night. The urban IWV distribution differs completely, with an urban IWV excess on average between 1600 and 0600 UTC (with a maximum of about 1.5 kg m−2 at 0600 and 1700 UTC). No IWV difference between the urban and rural areas is found in the middle of the day. The numerical simulations reproduce accurately the urban IWV anomaly.
Shallow surface wind convergence associated with the UHI during nighttime provides moisture from the rural areas. Urban areas are therefore under wind convergence for most of the time. The rural water vapour sources and the depth of the convergence control the amplitude of the urban IWV excess. At about 1200 UTC, entrainment at the top of the urban boundary layer is the key process that inhibits the urban IWV excess observed at night.Numéro de notice : A2009-589 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.446 Date de publication en ligne : 10/07/2009 En ligne : https://doi.org/10.1002/qj.446 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96192
in Quarterly Journal of the Royal Meteorological Society > vol 135 n° 642 (July 2009 Part A) . - pp 1266 - 1276[article]Horizontal and vertical interseismic velocity fields in the Vanuatu subduction zone from GPS measurements: Evidence for a central Vanuatu locked zone / Nicolas Bergeot in Journal of geophysical research : Solid Earth, Vol 114 n° B6 (June 2009)
[article]
Titre : Horizontal and vertical interseismic velocity fields in the Vanuatu subduction zone from GPS measurements: Evidence for a central Vanuatu locked zone Type de document : Article/Communication Auteurs : Nicolas Bergeot, Auteur ; Marie-Noëlle Bouin , Auteur ; Michel Diament , Auteur ; Bernard Pelletier, Auteur ; M. Régnier, Auteur ; Stéphane Calmant, Auteur ; Valérie Ballu, Auteur Année de publication : 2009 Article en page(s) : 20 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] champ de vitesse
[Termes IGN] coordonnées GPS
[Termes IGN] subduction
[Termes IGN] tectonique des plaques
[Termes IGN] VanuatuRésumé : (auteur) We analyzed interseismic velocity fields along the Vanuatu arc subduction zone from more than 45 GPS station measurements spanning 15 years. Convergence with respect to the Australian plate (AP) is normal to the trench, with amplitudes that vary greatly from a maximum of 170 mm a−1 at Vanikoro to 27 mm a−1 facing the D'Entrecasteaux Ridge (DER). Motions expressed relative to the Pacific plate (PP) highlight arc segmentation. Both the northern and southern segments undergo back‐arc spreading in a roughly NE‐SW direction, rotating anticlockwise and clockwise, respectively, while the central block moves eastward at a faster rate with respect to the PP than to the AP. More convergence is therefore accommodated at the eastern bound of the arc than at the Vanuatu trench. A right lateral strike‐slip movement (26 ± 1 mm a−1) along a zone normal to the trench (direction N70°) is necessary to accommodate the rate variation between the central and southern parts of the arc. Horizontal and vertical rates indicate partitioning between Malekula–southernmost Santo and central‐northern Santo blocks. Simple elastic modeling of the interseismic stage deformation gives locked zone characteristics (25° dip and 50 km width) and a 54 mm a−1 long‐term convergence rate between the AP and the central part of the Vanuatu arc from GPS horizontal and vertical velocities estimated south of the DER. The modeling does not fit the observed velocities facing the DER, probably because it does not account for the inelastic deformation associated with buoyant ridge subduction and back‐arc thrusting. Numéro de notice : A2009-586 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2007JB005249 Date de publication en ligne : 23/06/2009 En ligne : https://doi.org/10.1029/2007JB005249 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90613
in Journal of geophysical research : Solid Earth > Vol 114 n° B6 (June 2009) . - 20 p.[article]Documents numériques
en open access
Horizontal and vertical interseismic velocity fields ... - pdf éditeurAdobe Acrobat PDF Mesoscale GPS tomography applied to the 12 June 2002 convective initiation event of IHOP_2002 / Cédric Champollion in Quarterly Journal of the Royal Meteorological Society, vol 135 n° 640 (April 2009 part A)PermalinkAnomalous harmonics in the spectra of GPS position estimates / Jim Ray in GPS solutions, vol 12 n° 1 (January 20008)PermalinkPermalinkPermalinkLeast-square variance component estimation / AliReza Amiri-Simkooei (2007)PermalinkIntegration of GPS and remote sensing into GIS: a case study of rectifying satellite imagery using uncorrected coordinates in different scenes / J. Gao in Geocarto international, vol 21 n° 4 (December 2006 - February 2007)PermalinkA new combined European permanent network station coordinates solution / Natalia Panafidina in Journal of geodesy, vol 80 n° 7 (October 2006)PermalinkNicht-lineare Sensitivitätsanalyse gezeigt an Beispielen zu bewegten Objekten / Volker Schwieger (2005)PermalinkBlocs équipés de mesures GPS et inertielles, bilan des essais Applanix IGN, mise en place cartographique / Philippe Hottier in Revue Française de Photogrammétrie et de Télédétection, n° 175 (Septembre 2004)PermalinkPermalink