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On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state / Alexey Androsov in Journal of geodesy, vol 93 n° 2 (February 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 2 (February 2019) . - pp 141 - 157 Titre : On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state Type de document : Article/Communication Auteurs : Alexey Androsov, Auteur ; Lars Nerger, Auteur ; Reiner Schnur, Auteur ; Alberta Albertella, Auteur ; Reiner Rummel, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 141 - 157 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] assimilation des données [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] données altimétriques [Termes descripteurs IGN] données CHAMP [Termes descripteurs IGN] données GOCE [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] filtre de Kalman [Termes descripteurs IGN] geoïde marin [Termes descripteurs IGN] géoïde terrestre [Termes descripteurs IGN] hauteurs de mer [Termes descripteurs IGN] modèle de simulation [Termes descripteurs IGN] modèle océanographique [Termes descripteurs IGN] océanographie dynamique [Termes descripteurs IGN] salinité [Termes descripteurs IGN] température de surface de la mer Résumé : (auteur) General ocean circulation models are not perfect. Forced with observed atmospheric fluxes they gradually drift away from measured distributions of temperature and salinity. We suggest data assimilation of absolute dynamical ocean topography (DOT) observed from space geodetic missions as an option to reduce these differences. Sea surface information of DOT is transferred into the deep ocean by defining the analysed ocean state as a weighted average of an ensemble of fully consistent model solutions using an error-subspace ensemble Kalman filter technique. Success of the technique is demonstrated by assimilation into a global configuration of the ocean circulation model FESOM over 1 year. The dynamic ocean topography data are obtained from a combination of multi-satellite altimetry and geoid measurements. The assimilation result is assessed using independent temperature and salinity analysis derived from profiling buoys of the AGRO float data set. The largest impact of the assimilation occurs at the first few analysis steps where both the model ocean topography and the steric height (i.e. temperature and salinity) are improved. The continued data assimilation over 1 year further improves the model state gradually. Deep ocean fields quickly adjust in a sustained manner: A model forecast initialized from the model state estimated by the data assimilation after only 1 month shows that improvements induced by the data assimilation remain in the model state for a long time. Even after 11 months, the modelled ocean topography and temperature fields show smaller errors than the model forecast without any data assimilation. Numéro de notice : A2019-076 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1151-1 date de publication en ligne : 12/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1151-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92190 [article]

Post-1980 shifts in the sensitivity of boreal tree growth to North Atlantic Ocean dynamics and seasonal climate / Clémentine Ols in Global and Planetary Change, vol 165 (June 2018)  

Public [article]  inGlobal and Planetary Change > vol 165 (June 2018) . - pp 1 - 12 Titre : Post-1980 shifts in the sensitivity of boreal tree growth to North Atlantic Ocean dynamics and seasonal climate Type de document : Article/Communication Auteurs : Clémentine Ols , Auteur ; Valérie Trouet, Auteur ; Martin P. Girardin, Auteur ; Annika Hofgaard, Auteur ; Yves Bergeron, Auteur ; Igor Drobyshev, Auteur Année de publication : 2018 Article en page(s) : pp 1 - 12 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] analyse de sensibilité [Termes descripteurs IGN] Atlantique Nord [Termes descripteurs IGN] cerne [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] climat [Termes descripteurs IGN] croissance végétale [Termes descripteurs IGN] dendrochronologie [Termes descripteurs IGN] forêt boréale [Termes descripteurs IGN] inventaire forestier étranger (données) [Termes descripteurs IGN] océanographie dynamique [Termes descripteurs IGN] Picea abies [Termes descripteurs IGN] picea mariana [Termes descripteurs IGN] puits de carbone [Termes descripteurs IGN] Québec (Canada) [Termes descripteurs IGN] Suède [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) The mid-20th century changes in North Atlantic Ocean dynamics, e.g. slow-down of the Atlantic meridional overturning thermohaline circulation (AMOC), have been considered as early signs of tipping points in the Earth climate system. We hypothesized that these changes have significantly altered boreal forest growth dynamics in northeastern North America (NA) and northern Europe (NE), two areas geographically adjacent to the North Atlantic Ocean. To test our hypothesis, we investigated tree growth responses to seasonal large-scale oceanic and atmospheric indices (the AMOC, North Atlantic Oscillation (NAO), and Arctic Oscillation (AO)) and climate (temperature and precipitation) from 1950 onwards, both at the regional and local levels. We developed a network of 6876 black spruce (NA) and 14437 Norway spruce (NE) tree-ring width series, extracted from forest inventory databases. Analyses revealed post-1980 shifts from insignificant to significant tree growth responses to summer oceanic and atmospheric dynamics both in NA (negative responses to NAO and AO indices) and NE (positive response to NAO and AMOC indices). The strength and sign of these responses varied, however, through space with stronger responses in western and central boreal Quebec and in central and northern boreal Sweden, and across scales with stronger responses at the regional level than at the local level. Emerging post-1980 associations with North Atlantic Ocean dynamics synchronized with stronger tree growth responses to local seasonal climate, particularly to winter temperatures. Our results suggest that ongoing and future anomalies in oceanic and atmospheric dynamics may impact forest growth and carbon sequestration to a greater extent than previously thought. Cross-scale differences in responses to North Atlantic Ocean dynamics highlight complex interplays in the effects of local climate and ocean-atmosphere dynamics on tree growth processes and advocate for the use of different spatial scales in climate-growth research to better understand factors controlling tree growth. Numéro de notice : A2018-662 Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.gloplacha.2018.03.006 date de publication en ligne : 18/03/2018 En ligne : https://doi.org/10.1016/j.gloplacha.2018.03.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93844 [article]

Mission design, operation and exploitation of the gravity field and steady-state ocean circulation explorer mission / R. Floberghagen in Journal of geodesy, vol 85 n° 11 (November /2011)  

Public [article]  inJournal of geodesy > vol 85 n° 11 (November /2011) . - pp 749 - 758 Titre : Mission design, operation and exploitation of the gravity field and steady-state ocean circulation explorer mission Type de document : Article/Communication Auteurs : R. Floberghagen, Auteur ; M. Fehringer, Auteur ; D. Lamarre, Auteur ; D. Muzi, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 749 - 758 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] données GOCE [Termes descripteurs IGN] géoïde terrestre [Termes descripteurs IGN] GOCE [Termes descripteurs IGN] gradient de gravitation [Termes descripteurs IGN] gradiomètre [Termes descripteurs IGN] gravimétrie spatiale Résumé : (Auteur) The European Space Agency’s Gravity field and steady-state ocean circulation explorer mission (GOCE) was launched on 17 March 2009. As the first of the Earth Explorer family of satellites within the Agency’s Living Planet Programme, it is aiming at a better understanding of the Earth system. The mission objective of GOCE is the determination of the Earth’s gravity field and geoid with high accuracy and maximum spatial resolution. The geoid, combined with the de facto mean ocean surface derived from twenty-odd years of satellite radar altimetry, yields the global dynamic ocean topography. It serves ocean circulation and ocean transport studies and sea level research. GOCE geoid heights allow the conversion of global positioning system (GPS) heights to high precision heights above sea level. Gravity anomalies and also gravity gradients from GOCE are used for gravity-to-density inversion and in particular for studies of the Earth’s lithosphere and upper mantle. GOCE is the first-ever satellite to carry a gravitational gradiometer, and in order to achieve its challenging mission objectives the satellite embarks a number of world-first technologies. In essence the spacecraft together with its sensors can be regarded as a spaceborne gravimeter. In this work, we describe the mission and the way it is operated and exploited in order to make available the best-possible measurements of the Earth gravity field. The main lessons learned from the first 19 months in orbit are also provided, in as far as they affect the quality of the science data products and therefore are of specific interest for GOCE data users. Numéro de notice : A2011-467 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0498-3 date de publication en ligne : 18/10/2011 En ligne : https://doi.org/10.1007/s00190-011-0498-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31361 [article]

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Physically consistent system model for the study of the Earth's rotation, surface deformation and gravity field parameters / A. Hense (2009)

Public Titre : Physically consistent system model for the study of the Earth's rotation, surface deformation and gravity field parameters : scientific results of the DFG project Type de document : Monographie Auteurs : A. Hense, Auteur ; J. Sündermann, Auteur ; Hermann Drewes, Auteur ; et al., Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 2009 Collection : DGK - B Sous-collection : Angewandte Geodäsie num. 317 Importance : 53 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-8596-1 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] circulation atmosphérique [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] déformation de la croute terrestre [Termes descripteurs IGN] modèle hydrographique [Termes descripteurs IGN] modèle physique [Termes descripteurs IGN] pesanteur terrestre [Termes descripteurs IGN] rotation de la Terre [Termes descripteurs IGN] surcharge océanique [Termes descripteurs IGN] terme de Chandler Résumé : (Auteur) [introduction] This report is the final report of a serie of projects which studied the Earth's rotational parameters angular momentum, tensor of inertia as well as related variables of the Earth's gravitational field. A system view has been taken by trying to incorporate the contributions from the various subsystems of the Earth system in a physically consistent way. This introduction will highlight the project history and performance since 1996 and the state of the art in 2000. Note de contenu : 1. Introduction 1.1 The projects 1.2 Historical overview and motivations 2. Models of subsystems 2.1 Atmosphere models ECHAM 2.1.1 ECHAM5 2.1.2 Stand-alone atmosphere 20th century simulation 2.1.3 Results 2.2 Ocean model OMCT 2.3 Hydrological Discharge Model HDM 2.3.1 Continental hydrology modelling 2.3.1.1 SLS model component 2.3.1.2 HDM model component 2.3.1.3 Atmospheric forcing data 2.3.2 Results 2.3.2.1 Implementation of a 3-D relief model 2.3.2.2 Calculation of gravity field coefficients 2.3.2.3 Test simulations and validation of continental discharge with ECHAM4 and NCEP 2.3.2.4 Verification of simulated continental runoff (control runs) 2.3.2.5 Interface adaptation and verification of mass conservation at the boundaries in the coupled model system 2.3.2.6 Validation and analysis of continental water mass transports of ECOCTH 2.3.2.7 Statistical analysis and validation of simulated gravity field variations 2.3.2.8 Global water balance 2.3.3 Summary 3. Models of the coupled system 3.1 Coupled atmosphere-hydrosphere model ECOCTH 3.1.1 Model description 3.1.2 Validation 3.1.2.1 The lunisolar ocean tides 3.1.2.2 Global ocean circulation 3.1.2.3 Tropical variability and global warming 3.1.3 Results 3.1.3.1 Inter-annual variations and secular trends in length of day 3.2 Dynamic model of Earth rotation, gravity and surface deformation DyMEG 3.2.1 Numerical solution of the Liouville differential equation 3.2.2 Inverse model for surface deformations of the solid Earth due to mass loads 4. Results for Earth rotation, surface deformation and gravity 4.1 Validation of DyMEG with NCEP and ECCO 4.2 Results of DyMEG with ECOCTH forcing 5. Scientific highlights 5.1 Tidal mixing 5.1.1 Tidal mixing in OMCT2 5.1.2 Effect of tidal mixing on ocean water mass properties 5.2 Secular and decadal variations 5.2.1 Coupled simulation of Earth Rotation Parameters 5.2.2 Axial AAM long-term trends in 21st century scenario runs 5.3 Forcing mechanisms of the Chandler oscillation 5.3.1 Atmospheric and hydrospheric excitation of the Chandler oscillation 5.3.2 Noise as excitation mechanism of the Chandler oscillation 6. Conclusions and outlook 7. References Numéro de notice : 15454 Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62723

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GOCE : obtaining a portrait of Earth's most intimate features / M. Drinkwater in ESA bulletin, n° 133 (February 2008)  

Public [article]  inESA bulletin > n° 133 (February 2008) . - pp 4 - 13 Titre : GOCE : obtaining a portrait of Earth's most intimate features Type de document : Article/Communication Auteurs : M. Drinkwater, Auteur ; Roger Haagmans, Auteur ; M. Kern, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 4 - 13 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Missions spatiales [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] données GOCE [Termes descripteurs IGN] géoïde [Termes descripteurs IGN] GOCE [Termes descripteurs IGN] gradiomètre [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] nivellement [Termes descripteurs IGN] satellite d'observation de la Terre Résumé : (Auteur) Known as ESA's "Gravity Mission", GOCE represent a blend of revolutionary new technology, designed to open a new chapter in what has historically been one of the most intriguing issues confronting science. Scheduled for launch in mid-2008, Goce will deliver data about the fundamental force of nature, which will benefit a broad range of applications in Earth sciences. Copyright European Space Agency Numéro de notice : A2008-124 Thématique : IMAGERIE/POSITIONNEMENT Nature : Article En ligne : http://www.esa.int/esapub/bulletin/bulletin133/bul133b_drinkwater.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29119 [article]

GOCE's measurements of the gravity field and beyond / R. Floberghaben in ESA bulletin, n° 133 (February 2008)  

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Marine GIS: identification of mesoscale oceanic thermal fronts / V.D. Valavanis in International journal of geographical information science IJGIS, vol 19 n° 10 (november 2005)

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A global kinetic spatial data structure for a marine simulation / Mir Abolfazl Mostafavi in International journal of geographical information science IJGIS, vol 18 n° 3 (april - may 2004)

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Atmosphärische und ozeanische Einflüsse auf die Rotation der Erde - Nummerische Untersuchungen mit einem dynamischen Erdsystemmodell / Florian Seitz (2004)

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Satellite Altimetry for geodesy, geophysics and oceanography / C. Hwang (2004)

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Topex-Poséïdon, mesureur des océans / J.P. Penot in BT, Bibliothèque de Travail, n° 1103 (01/12/1998)

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Third ERS Symposium on space at the service of our environment, Florence, Italy, 14 - 21 March 1997, 3. Volume 3 / T.D. Guyenne (1997)

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Evaluation altimétrique du modèle océanique du NMC [National Meteorologic Center] / J.e Harris in Aviso altimetry newsletter, n° 4 (01/02/1996)

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Low-frequency sea-level variability and geostrophic current derived from TOPEX/POSEIDON satellite in the Indian Ocean / A. S. Atmadipoera (1995)

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Modelling oceanic climate interactions: Proceedings of the NATO advanced Study Institute, Les Houches, France, February 23-26, 1992, 11. Volume 11 / A. Chedin (1993)

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