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Validating a new GNSS-based sea level instrument (CalNaGeo) at Senetosa Cape / Pascal Bonnefond in Marine geodesy, vol 45 n° 2 (March 2022)  

Public [article]  inMarine geodesy > vol 45 n° 2 (March 2022) . - pp 121 - 150 Titre : Validating a new GNSS-based sea level instrument (CalNaGeo) at Senetosa Cape Type de document : Article/Communication Auteurs : Pascal Bonnefond, Auteur ; Olivier Laurain, Auteur ; Pierre Exertier, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 121 - 150 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] altimétrie satellitaire par radar [Termes IGN] carte bathymétrique [Termes IGN] Corse [Termes IGN] étalonnage d'instrument [Termes IGN] geoïde marin [Termes IGN] hauteurs de mer [Termes IGN] instrument de géodésie [Termes IGN] marégraphe [Termes IGN] niveau de la mer [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] surface de la mer Résumé : (auteur) The geodetic Corsica site was set up in 1998 in order to perform altimeter calibration of the TOPEX/Poseidon (T/P) mission and subsequently, Jason-1, OSTM/Jason-2, Jason-3 and more recently Sentinel-6 Michael Freilich (launched on November, 21 2020). The aim of the present study held in June 2015 is to validate a recently developed GNSS-based sea level instrument (called CalNaGeo) that is designed with the intention to map Sea Surface Heights (SSH) over large areas. This has been undertaken using the well-defined geodetic infrastructure deployed at Senetosa Cape, and involved the estimation of the stability of the waterline (and thus the instantaneous separation of a GNSS antenna from water level) as a function of the velocity at which the instrument is towed. The results show a largely linear relationship which is approximately 1 mm/(m/s) up to a maximum practical towing speed of ∼10 knots (∼5 m/s). By comparing to the existing “geoid” map, it is also demonstrated that CalNaGeo can measure a sea surface slope with a precision better than 1 mm/km (∼2.5% of the physical slope). Different processing techniques are used and compared including GNSS Precise Point Positioning (PPP, where the goal is to extend SSH mapping far from coastal GNSS reference stations) showing an agreement at the 1-2 cm level. Numéro de notice : A2022-212 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2021.2013355 Date de publication en ligne : 28/12/2021 En ligne : https://doi.org/10.1080/01490419.2021.2013355 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100046 [article]

Validating geoid models with marine GNSS measurements, sea surface models, and additional gravity observations in the Gulf of Finland / Timo Saari in Marine geodesy, vol 44 n° 3 (May 2021)  

Public [article]  inMarine geodesy > vol 44 n° 3 (May 2021) . - pp 196 - 214 Titre : Validating geoid models with marine GNSS measurements, sea surface models, and additional gravity observations in the Gulf of Finland Type de document : Article/Communication Auteurs : Timo Saari, Auteur ; Mirjam Bilker-Koivula, Auteur ; Hannu Koivula, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 196 - 214 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Finlande [Termes IGN] géodésie marine [Termes IGN] geoïde marin [Termes IGN] hauteur ellipsoïdale [Termes IGN] mesurage par GNSS [Termes IGN] modèle de géopotentiel [Termes IGN] nivellement [Termes IGN] surface de la mer Résumé : (auteur) Traditionally, geoid models have been validated using GNSS-levelling benchmarks on land only. As such benchmarks cannot be established offshore, marine areas of geoid models must be evaluated in a different way. In this research, we present a marine GNSS/gravity campaign where existing geoid models were validated at sea areas by GNSS measurements in combination with sea surface models. Additionally, a new geoid model, calculated using the newly collected marine gravity data, was validated. The campaign was carried out with the marine geology research catamaran Geomari (operated by the Geological Survey of Finland), which sailed back and forth the eastern part of the Finnish territorial waters of the Gulf of Finland during the early summer of 2018. From the GNSS and sea surface data we were able to obtain geoid heights at sea areas with an accuracy of a few centimetres. When the GNSS derived geoid heights are compared with geoid heights from the geoid models differences between the respective models are seen in the most eastern and southern parts of the campaign area. The new gravity data changed the geoid model heights by up to 15 cm in areas of sparse/non-existing gravity data. Numéro de notice : A2021-387 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2021.1889727 Date de publication en ligne : 11/03/2021 En ligne : https://doi.org/10.1080/01490419.2021.1889727 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97670 [article]

GEBCO Gridded Bathymetric Datasets for mapping Japan Trench geomorphology by means of GMT scripting toolset / Polina Lemenkova in Geodesy and cartography, vol 46 n° 3 (October 2020)  

Public [article]  inGeodesy and cartography > vol 46 n° 3 (October 2020) . - pp 98 - 112 Titre : GEBCO Gridded Bathymetric Datasets for mapping Japan Trench geomorphology by means of GMT scripting toolset Type de document : Article/Communication Auteurs : Polina Lemenkova, Auteur Année de publication : 2020 Article en page(s) : pp 98 - 112 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie thématique [Termes IGN] carte bathymétrique [Termes IGN] déformation de la croute terrestre [Termes IGN] données bathymétriques [Termes IGN] données maillées [Termes IGN] geoïde marin [Termes IGN] géomorphologie [Termes IGN] GMT [Termes IGN] Japon [Termes IGN] modèle numérique de surface [Termes IGN] Pacifique (océan) Résumé : (auteur) The study investigated geomorphology of the Japan Trench located east of Japan, Pacific Ocean. A high-resolution GEBCO Gridded Bathymetric Dataset was used for modeling, mapping and visualization. The study aimed to compare and analyse variations in the geomorphic structures of the two parts of the trench and to visualize variations in the geological, geophysical and bathymetric settings. Technically, the cartographic work was performed using scripting based on the Generic Mapping Toolset (GMT). Modelled cross-sectioning orthogonal profiles transecting the trench in a perpendicular direction were automatically digitized and graphed in the two segments. The results of the bathymetric analysis shown that the southern part is shallower: with deeper values in absolute (139 samples between –7000 to –8000 m) and statistical records (the most frequent values are within –5500 to –5800 m) comparing to the northern segment (–5300 to –5500 m). The geomorphological analysis shows a more complicated relief in the northern part of the trench, which has a higher seismic activity. The southern part has a gentler slope on the Honshu island side. The geoid modeling along the trench ranges in 0–20 mGal. The highest values are recorded by the Honshu Island (>40 mGal). The rest of the area has rather moderate undulations (20–40 mGal). The free-air marine gravity of the Sea of Japan is Numéro de notice : A2020-782 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3846/gac.2020.11524 Date de publication en ligne : 08/10/2020 En ligne : https://doi.org/10.3846/gac.2020.11524 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96477 [article]

Validation of marine geoid models by utilizing hydrodynamic model and shipborne GNSS profiles / Sander Varbla in Marine geodesy, Vol 43 n° 2 (March 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 2 (March 2020) . - pp 134 - 162 Titre : Validation of marine geoid models by utilizing hydrodynamic model and shipborne GNSS profiles Type de document : Article/Communication Auteurs : Sander Varbla, Auteur ; Artu Ellmann, Auteur ; Nicole Delpeche-Ellmann, Auteur Année de publication : 2020 Article en page(s) : pp 134 - 162 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Baltique, mer [Termes IGN] données marégraphiques [Termes IGN] force de gravitation [Termes IGN] geoïde marin [Termes IGN] instrument embarqué [Termes IGN] instrumentation GNSS [Termes IGN] levé gravimétrique [Termes IGN] navire [Termes IGN] niveau de la mer [Termes IGN] simulation hydrodynamique Résumé : (auteur) An essential role of the FAMOS international cooperation project is to obtain new marine gravity observations over the Baltic Sea for improving gravimetric geoid modelling. To achieve targeted 5 cm modelling accuracy, it is important to acquire new gravimetric data, as the existing data over some regions are inaccurate and sparse. As the accuracy of contemporary geoid models over marine areas remains unknown, it is important to evaluate geoid modelling outcome by independent data. Thus, this study presents results of a shipborne marine gravity and GNSS campaign for validation of existing geoid models conducted in the eastern section of the Baltic Sea. Challenging aspects for utilizing shipborne GNSS profiles tend to be with quantifying vessel’s attitude, processing of noise in the data and referencing to the required datum. Consequently, the novelty of this study is in the development of methodology that considers the above-mentioned challenges. In addition, tide gauge records in conjunction with an operational hydrodynamic model are used to identify offshore sea level dynamics during the marine measurements. The results show improvements in geoid modelling due to new marine gravimetric data. It is concluded that the marine GNSS profiles can potentially provide complementary constraints in problematic geoid modelling areas. Numéro de notice : A2020-051 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2019.1701153 Date de publication en ligne : 20/01/2020 En ligne : https://doi.org/10.1080/01490419.2019.1701153 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94918 [article]

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 IGN] assimilation des données [Termes IGN] circulation océanique [Termes IGN] données altimétriques [Termes IGN] données CHAMP [Termes IGN] données GOCE [Termes IGN] données GRACE [Termes IGN] filtre de Kalman [Termes IGN] geoïde marin [Termes IGN] géoïde terrestre [Termes IGN] hauteurs de mer [Termes IGN] modèle de simulation [Termes IGN] modèle océanographique [Termes IGN] océanographie dynamique [Termes IGN] salinité [Termes 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 Affiliation des auteurs : non IGN 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]

Reconciling upper mantle seismic velocity and density structure below ocean basins / Isabelle Panet (2019)

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Using models of the ocean's mean dynamic topography to identify errors in coastal geodetic levelling / M. S. Filmer in Marine geodesy, vol 37 n° 1 (March - May 2014)  

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Lowest astronomical tide in the North Sea derived from a vertically referenced shallow water model, and an assessment of its suggested sense of safety / D. Slobbe in Marine geodesy, vol 36 n° 1 (January - March 2013)  

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Assessment of systematic errors in the computation of gravity gradients from satellite altimeter data / Johannes Bouman in Marine geodesy, vol 34 n° 2 (April - June 2011)  

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Développement d’un système léger de gravimétrie mobile : LiMoG / José Cali in Revue des Systèmes (RS) - Instrumentation - Mesure - Métrologie (Série I2M), vol 10 n° 3-4 (Juillet - Décembre 2010)  

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Sea surface topography and marine geoid by airborne laser altimetry and shipborne ultrasound altimetry / Philippe Limpach (2010)  

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Taking the measure of Earth / J. Benveniste in ESA bulletin, n° 128 (November 2006)  

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Determination of evolution of the altimetric mean level of western mediterranean from the Jason-1 Data: comparison with analysis of the tidal gauge measurements / M. Haddad in Bulletin des sciences géographiques, n° 18 (octobre 2006)

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La Terre vue de l'espace / Anny Cazenave (2004)

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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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