The southern oceans of the world have not been well surveyed generally, in contrast with oceans of the northern hemisphere. Data from the relatively new Seasat, which is a radar altimeter flown on a satellite platform, has recently provided bathymetric estimates for the southern oceans (Nature, 304, 407, 1983). The Seasat data provides a planning data base for future ship surveys to obtain precisely and accurately charted sea-floor topography.
The analysis of a 70-day data set originally collected over the 100-day period from July 5 to October 10, 1978, has revealed a number of distinct bathymetric features that had not been observed before. For example, the new data showed a major rise, or geoid high, that exists east of the Louisville Ridge between latitudes 38° and 41°S, and longitudes 160° and 150°W. The Louisville Ridge itself was found to be a nearly continuous feature composed of short ridge segments. A volcanic rather than a fracture zone origin is suggested by this topography.