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Regional Models


  Authors: H. Shih, et al.     Created: 2015    Resp: C. Hwang  
      Status: PUBLIC    
The geoid model for Tahiti and Moorea in French Polynesia covers the area 17.0-18.4°S and 148.8-150.2°E with a grid resolution of 9" x 9". The gravimetric model is based on land and airborne gravity data, as well as marine gravity derived from satellite altimetry. It is computed by band-limited least-squares collocation in the framework of a remove-restore procedure. The reference global gravity model is EGM2008 up to degree and order 1500. The used digital terrain model has a grid resolution of 1' x 1' and is constructed by combining 5 x 5 m land elevations from Service de l’Aménagement et de l’Urbanisme of French Polynesia and 30" x 30" ocean depths from the SRTM30_PLUS product. The conversion from quasi-geoid to geoid is implemented too. The resulting gravimetric model is then adapted by least-squares collocation to GPS/levelling data at 48 benchmarks on Tahiti and 6 benchmarks on Moorea. The orthometric heights are referred to the vertical datum of Nivellement General de Polynesie Francaise (NGPF), while the ellipsoidal heights are referred to the GRS80 ellipsoid in the frame of Réseau Géodésique de Polynésie Française (RGPF) that is a local solution of ITRF92. The gravimetric model fits the overall 54 GPS/levelling points with 3.6 cm standard deviation, while the hybrid solution fits them with 0.4 cm standard deviation.

H. Shih, C. Hwang, J. Barriot, M. Mouyen, P. Corréia, D. Lequeux, L. Sichoix (2015). High-resolution gravity and geoid models in Tahiti obtained from new airborne and land gravity observations: data fusion by spectral combination. Earth, Planets and Space, 67, No. 124. DOI: 10.1186/s40623-015-0297-9