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Comparison of different global DTMs and GGMs over Sri Lanka / Weeramuni Javana Praboni De Silva in Journal of applied geodesy, vol 17 n° 1 (January 2023)  

Public [article]  inJournal of applied geodesy > vol 17 n° 1 (January 2023) . - pp 29 - 38 Titre : Comparison of different global DTMs and GGMs over Sri Lanka Type de document : Article/Communication Auteurs : Weeramuni Javana Praboni De Silva, Auteur ; Herath Mudiyanselage Indika Prasanna, Auteur Année de publication : 2023 Article en page(s) : pp 29 - 38 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] géoïde altimétrique [Termes IGN] MERIT [Termes IGN] MNS ASTER [Termes IGN] MNS SRTM [Termes IGN] modèle de géopotentiel [Termes IGN] Sri Lanka [Vedettes matières IGN] Altimétrie Résumé : (auteur) Digital Elevation Models (DEMs) are real-world geographical databases that are important in studying many Earth related topics. Because the vertical accuracy of global DEMs differs across regions due to various reasons, acquiring reliable heights for a region using global height models is crucial. The objective of this study is to compare and assess the most reliable global height model for Sri Lanka. The official height system in Sri Lanka is the Mean Sea Level (MSL) based orthometric height system. In this study, the quality of ASTER, SRTM, NASADEM, MERIT, and DEMs compiled from digitized contour data of Sri Lanka was evaluated using the known heights of the Fundamental Benchmarks (FBMs) of Sri Lanka. In addition, recently published high-resolution Global Geopotential Models (GGMs) were used for the accuracy assessments of gravity related quantities computed using DEMs. The SGG-UGM-2 GGM, which showed the minimum STD and RMSE of geoid undulation difference was found as the best fit GGM over Sri Lanka. It was found that the NASADEM at its highest resolution, which gave the lowest RMSE of 2.954 m was the best global DEM for Sri Lanka. Numéro de notice : A2023-050 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2022-0026 Date de publication en ligne : 07/11/2022 En ligne : https://doi.org/10.1515/jag-2022-0026 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102376 [article]

Temperature and humidity effects on CG-6 gravity observations / P. I. A. Weerasinghe in Journal of applied geodesy, vol 15 n° 3 (July 2021)  

Public [article]  inJournal of applied geodesy > vol 15 n° 3 (July 2021) . - pp 225 - 231 Titre : Temperature and humidity effects on CG-6 gravity observations Type de document : Article/Communication Auteurs : P. I. A. Weerasinghe, Auteur ; Herath Mudiyanselage Indika Prasanna, Auteur Année de publication : 2021 Article en page(s) : pp 225 - 231 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] corrélation linéaire [Termes IGN] force de gravitation [Termes IGN] gravimètre [Termes IGN] humidité de l'air [Termes IGN] instrument de mesure [Termes IGN] Sri Lanka [Termes IGN] température de l'air [Termes IGN] thermomètre Résumé : (Auteur) The CG6 is an automated gravity meter that has a worldwide measurement range of over 8000 mGals and a reading resolution of 0.0001 mGal. Some factors that may influence the gravity readings are corrected by the instrument’s software. In this paper, the effects of the ambient temperature and humidity changes on the CG-6’s gravity measurements were investigated with the aim of reducing the uncertainty which remains in gravity measurements in microgal level, and giving recommendations for more accurate results. A controlled heating experiment was used to determine the impact of ambient temperature on gravity and 12 hours of continuous gravity observations were used to identify the impact of humidity on gravity measurements. It was observed that the sensor temperature and the gravity reading were highly correlated with the ambient temperature. The linear correlation with R2 > 0.94 and R2 > 0.90 were found for the corrected gravity reading and the residual sensor temperature variations respectively with the ambient temperature when heating. It was demonstrated that the calculated ambient temperature correction, −0.0011 mGal/oC, is more stable than the correction given by the instrument in terms of standard deviation though the impact of humidity on gravity reading was not clear. Numéro de notice : A2021-468 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2020-0047 Date de publication en ligne : 28/04/2021 En ligne : https://doi.org/10.1515/jag-2020-0047 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98106 [article]