Development of the first gravimetric geoid in the United Arab Emirates (UAE)
Eng. Adel Khaleefa Alshamsi
Military Survey Department
Abu Dhabi, UAE
Email: alshamsi@uaesurvey.ae
Eng. Abdulla Mohamed Alnaqbi
Military Survey Department
Abu Dhabi, UAE
Email: aalnaqbi@uaesurvey.ae
Abdulla Almansoor
Military Survey Department
Abu Dhabi, UAE
Email: ahr@uaesurvey.ae
Abstract For well-known practical reasons and scientific motivation in geodesy community, geoid model determination has been one of the prime objectives of geodetic scientists. The detail and high resolution gravimetric geoid of the UAE has been computed on Geodetic Reference System 1980 (GRS 1980) for the first time, using a combination of various source of gravity data, satellite derived potential coefficients, satellite altimetry, marine, and terrestrial gravity data. The UAE2003 geoid was calculated using an approximation to Helmert's second method of condensation, combined with the "remove-compute-restore" Fast Fourier Transform procedure, and the combined GRACE-EGM96 geopotential model as a foundation. The gravity anomalies ("remove") and the geoid undulations ("restore") were simultaneously computed by evaluating a spherical harmonic series, using EGM96 potential coefficients. Different reference field of global geopotential models has been tested in the grid 21º-27ºN, 50º-58ºE, finally the long-wave length and medium component of the geoidal undulation was computed using a combination of a new GRACE-derived field GGM01C, complete to degree and order 200 and EGM96, complete to degree and order 360. To improve the quality of the geoid in the marine area and alongside the UAE coast, marine data have been evaluated and subsequently combined with satellite altimeter gravity data.
GPS can be utilised for height interpolation and replace third order levelling which is tedious and time consuming. This paper will provide description of the methodology used for the computation of a gravimetric geoid of the UAE and the approach followed to fit the geoid to GPS- levelling points . The paper will also look at the future possibilities of connecting the different vertical networks available in the country using the GPS and the gravimetric geoid model .