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Regional Models

Colorado - USA (ColFFTWG-Curtin2019)

  Authors: S. Claessens, M. Filmer   Created: 2019    Resp: S. Claessens  
                       Status: PUBLIC   Licence: CC BY 4.0
The ColFFTWG-Curtin2019 gravimetric quasi-geoid and geoid models have been computed by the Curtin University, Perth, Australia. They have been worked out in the frame of the International Association of Geodesy Joint Working Group 2.2.2 "The 1 cm geoid experiment" and the so called "Colorado experiment". The area covered by the models is 250°E ≤ longitude ≤ 258°E, 35°N ≤ latitude ≤ 40°N with a grid spacing of 1' in both latitude and in longitude. Terrestrial and airborne free-air gravity anomalies were reduced by subtraction of gravity anomalies from the GO_CONS_GCF_2_DIR_R6 global gravity model (for pre-processing of the gravity data only) and a topographic correction based on the SRTM 3″ v4.1 model. These reduced data were simultaneously gridded by application of 3D least-squares collocation (LSC) with planar logarithmic covariance function, and then converted to Faye anomalies. The quasi-geoid computation was then computed with a remove-compute-restore technique, for which the xGEOID17RefB global gravity model was used. The 1D-FFT integration with Wong-Gore modified Stokes kernel was applied, where optimal modification parameters were determined from comparison to GPS-levelling data. The classical formula by Heiskanen and Moritz (1967) was used for the geoid/quasi-geoid separation. The accuracy of the quasi-geoid and geoid models, when compared against GSVS17 GPS/leveling, is equal to 3.2 cm and 4.1 cm, respectively.

S. Claessens, M. Filmer (2019). IHRS experiment Colorado - Results with the AUSGeoid2020 computation approach. Report of the Joint Working Group 2.2.2 "The 1 cm geoid experiment", pp.1-4
S. Claessens, M. Filmer (2020). Towards an International Height Reference System: insights from the Colorado experiment using AUSGeoid computation methods. Journal of Geodesy, 94, 52. DOI: 10.1007/s00190-020-01379-3