Topographic Mapping Using Topex Satellite Altimetry

Abstract

Radar altimeters were designed to collect height data over ocean surfaces where there are few sudden changes in elevation to send the instrument off-lock. Because land surfaces are not smooth over the fairly large footprint of present day satellite altimeter systems (typically 10 km), severe restrictions are placed on the information that can be obtained in most situations. The work presented here makes use of the free data from the Topex/Poseidon mission using a test site in the Saudi Arabian desert. The study was limited to an assessment of measurement accuracy and a feasibility study of using such data for mapping purposes. Results were compared with retracked elevation data and a digital terrain model over different types of terrain, varying from mountain to desert. It was found that, over desert areas, over 90% of the data contained valid difference height data, and it is concluded that, in principle, satellite altimetry could be used for accurate mapping purposes but that its use in all but a few cases will need to await the launch of instruments with greater spatial resolution, both in terms of footprint size and sample spacings.