Mapping of sea bottom topography over western offshore, India using TOPEX/ERS-1 altimeter data

As bathymetry and geoid are highly correlated in the 50-300 km range, the satellite-derived geoid can be used in the mapping of bathymetry. An attempt has been made to assess the accuracy of predicting sea bottom topography/bathymetry through a convolution model using satellite altimeter data over the Indian offshore region. The study uses TOPEX/POSEIDON as well as ERS-1 altimeter data, along with National Geophysical Data Centre (NGDC), U.S.A. ship-borne bathymetry data. The altimeter range data are corrected for atmospheric and oceanographic effects to generate the sea surface height (SSH) over the Indian offshore. The SSH along repeat altimeter passes over a period of 1 year are averaged to minimize the contribution due to dynamic sea surface topography in SSH. Cross-over corrections are applied to account for the orbital error in the altimetric observation. The corrected SSH has been used as an approximation to the marine geoid. The bathymetry is related with the geoid through a convolution model. The one-dimensional response function is computed in the frequency domain using some of the data tracks for which both bathymetry and geoid data are available. The accuracy of the developed model is then assessed by applying it over the rest of the tracks. (C) 1998 Elsevier Science Ltd. All rights reserved.