| Geosat ERM data concerning the Indian Ocean over a period of 26 months were processed with two different techniques of orbit error reduction in order to improve the accuracy of estimates of large-scale meridional sea-level variations. The first technique removes an along-track polynomial of degree 1 over approximately 5,000 km; the second removes an along-track once-per-revolution sine wave (approximately 40,000 km). Averaged over the Indian Ocean, the difference between the two estimates represents 43 % of the total variance and 31 % of the annual variance. This difference contains both oceanic and error signals. Sea-level variations from both techniques show an error with a spectral peak at 7-degrees-6 zonal wavelength, 317-day period, propagating... |
