{"title":"The determination of Thailand Geoid Model 2017 (TGM2017) from airborne and terrestrial gravimetry","authors":"Puttipol Dumrongchai, Chawis Srimanee, Nuttanon Duangdee, Jittrakorn Bairaksa","doi":"10.3319/tao.2021.08.23.01","DOIUrl":null,"url":null,"abstract":"The Royal Thai Survey Department and Chiang Mai University developed the Thailand geoid model 2017 (TGM2017) with a 1’ × 1’ grid to support the transformation between Global Navigation satellite System (GNSS) ellipsoid heights and Kolak-1915 vertical datum orthometric heights. TGM2017 was based on Thailand gravimetric geoid model 2017 (THAI17G) and 299 GNSS ellipsoidal heights co-located with Kolak-1915 heights. All terrestrial gravity data used for geoid computation came from the new national gravity network, consisting of 87 absolute and 9929 relative gravity stations at 10 – 25 km intervals, mostly along with existing roads. From 2016 to 2017, airborne gravity surveys were conducted at a 4000m-flight altitude and 10 km along-track spacing to acquire the gravity data over mountainous and inaccessible areas, including coastal and marine areas, at an estimated accuracy of 3.0 mGal. Long-wavelength geoid structure was controlled by the GOCE-EGM2008 combined model (GECO) and the Technical University of Denmark’s global marine gravity model 2013 (DTU13). All gravity data were combined and downward, using least-squares collocation with the residual terrain model reductions from a digital terrain elevation data level 2 (DTED2). THAI17G was determined by multi-band spherical Fast Fourier Transform and converted to TGM2017 with the 38.2cm root-mean-square (rms) fit of 299 GNSS/leveling co-points and a mean offset of 37.0 cm. This value represents the separation between Kolak-1915 and a global mean sea level. The evaluation of TGM2017 at 100 GNSS/leveling checkpoints shows the rms of 4.9 cm, consequently leading to reliable orthometric heights at a 10-cm accuracy level or better.","PeriodicalId":22259,"journal":{"name":"Terrestrial, Atmospheric and Oceanic Sciences","volume":null,"pages":null},"PeriodicalIF":0.8000,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Terrestrial, Atmospheric and Oceanic Sciences","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.3319/tao.2021.08.23.01","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 1
Abstract
The Royal Thai Survey Department and Chiang Mai University developed the Thailand geoid model 2017 (TGM2017) with a 1’ × 1’ grid to support the transformation between Global Navigation satellite System (GNSS) ellipsoid heights and Kolak-1915 vertical datum orthometric heights. TGM2017 was based on Thailand gravimetric geoid model 2017 (THAI17G) and 299 GNSS ellipsoidal heights co-located with Kolak-1915 heights. All terrestrial gravity data used for geoid computation came from the new national gravity network, consisting of 87 absolute and 9929 relative gravity stations at 10 – 25 km intervals, mostly along with existing roads. From 2016 to 2017, airborne gravity surveys were conducted at a 4000m-flight altitude and 10 km along-track spacing to acquire the gravity data over mountainous and inaccessible areas, including coastal and marine areas, at an estimated accuracy of 3.0 mGal. Long-wavelength geoid structure was controlled by the GOCE-EGM2008 combined model (GECO) and the Technical University of Denmark’s global marine gravity model 2013 (DTU13). All gravity data were combined and downward, using least-squares collocation with the residual terrain model reductions from a digital terrain elevation data level 2 (DTED2). THAI17G was determined by multi-band spherical Fast Fourier Transform and converted to TGM2017 with the 38.2cm root-mean-square (rms) fit of 299 GNSS/leveling co-points and a mean offset of 37.0 cm. This value represents the separation between Kolak-1915 and a global mean sea level. The evaluation of TGM2017 at 100 GNSS/leveling checkpoints shows the rms of 4.9 cm, consequently leading to reliable orthometric heights at a 10-cm accuracy level or better.
期刊介绍:
The major publication of the Chinese Geoscience Union (located in Taipei) since 1990, the journal of Terrestrial, Atmospheric and Oceanic Sciences (TAO) publishes bi-monthly scientific research articles, notes, correspondences and reviews in all disciplines of the Earth sciences. It is the amalgamation of the following journals:
Papers in Meteorological Research (published by the Meteorological Society of the ROC) since Vol. 12, No. 2
Bulletin of Geophysics (published by the Institute of Geophysics, National Central University) since No. 27
Acta Oceanographica Taiwanica (published by the Institute of Oceanography, National Taiwan University) since Vol. 42.