A HIGH-RESOLUTION GRAVIMETRIC GEOID IN THE STRAIT OF GIBRALTAR

A high-resolution gravimetric geoid model in the Strait of Gibraltar i s presented. The computations are based in a data set consisting of 10 4890 free-air gravity anomalies covering the area (33 < phi < 39, -10. 5 < lambda < 5.5). the OSU91A geopotential model and a Digital Terrain Model. The remove-restore technique, the Helmert second condensation reduction and the Stokes formula are applied. The computations are mad e with the spherical 1 D FFT.Discrete spectra of the kernel function a re used. In order to avoid circular convolution effects. 100% zero pad ding has been appended arounded the signal matrix. The result is a 256 x 512 grid referred to the GRS80 system. Comparison with previous geo ids in the same area shows an improvement in precision and reliability . The computed geoid is compared with geoid undulations obtained by GP S Levelling, and a precision of 1.0 ppm obtained.