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Accurate sea surface heights from Sentinel-3A and Jason-3 retrackers by incorporating high-resolution marine geoid and hydrodynamic models / Mir Abolfazl Mostafavi in Journal of geodetic science, vol 11 n° 1 (January 2021)  

Public [article]  inJournal of geodetic science > vol 11 n° 1 (January 2021) . - pp 58 - 74 Titre : Accurate sea surface heights from Sentinel-3A and Jason-3 retrackers by incorporating high-resolution marine geoid and hydrodynamic models Type de document : Article/Communication Auteurs : Mir Abolfazl Mostafavi, Auteur ; Nicole Delpeche-Ellmann, Auteur ; Artu Ellmann, Auteur Année de publication : 2021 Article en page(s) : pp 58 - 74 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Baltique, mer [Termes IGN] données altimétriques [Termes IGN] données Jason [Termes IGN] geoïde marin [Termes IGN] hauteurs de mer [Termes IGN] image Sentinel-3 [Termes IGN] océanographie spatiale [Termes IGN] relief de la surface de la mer Résumé : (auteur) One of the major challenges of satellite altimetry (SA) is to produce accurate sea surface heights data up to the shoreline, especially in geomorphologically complex sea areas. New advanced retracking methods are expected to deliver better results. This study examines the achievable accuracy of Sentinel-3A (S3A) and Jason-3 (JA3) standard retrackers (Ocean and MLE4) with that of improved retrackers adapted for coastal and sea ice conditions (ALES+ SAR for S3A and ALES+ for JA3). The validation of SA data was performed by the integration of tidegauges, hydrodynamic model and high-resolution geoidmodel. The geoid being a key component that links the vertical reference datum of the SA with other utilized sources. The method is tested in the eastern section of Baltic Sea. The results indicate that on average reliable sea surface height (SSH) data can be obtained 2–3 km from the coast-line for S3A (for both Ocean and ALES+SAR) whilst an average distance of 7–10 km for JA3 (MLE4 and ALES+) with a minimum distance of 3–4 km. In terms of accuracy, the RMSE (with respect to a corrected hydrodynamic model) of S3A ALES+ SAR and Ocean retrackers based SSH were 4–5cm respectively, whereas with the JA3 ALES+ and MLE4 associated SSH RMSE of 6–7 cm can be achieved. The ALES+and ALES+ SAR retrackers show SSH improvement within a range of 0.5–1 cm compared to the standard retrackers. This assessment showed that the adaptation of localized retrackers for the Baltic Sea (ALES+ and ALES+SAR) produced more valid observation closer to the coast than the standard retrackers and also improved the accuracy of SSH data. Numéro de notice : A2021-982 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jogs-2020-0120 Date de publication en ligne : 17/09/2021 En ligne : https://doi.org/10.1515/jogs-2020-0120 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100979 [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]