Marine gravity



The U.S. Navy satellite, GEOSAT (Figure 1) is third in the series of microwave altimeter satellites which make, or made, precise, direct observations of the marine geoid. GEOSAT, launched March 1985, is active today. Its two predecessors are NASA's Geos-3 mission which operated from 1975 through 1978 and NASA's SEASAT mission which functioned only during the summer of 1978. Each of the three has provided highly significant, abundant, new information about the gravity field of the oceans. As such, these missions have begun a revolution in marine geodesy and geophysics. One exemplary result of this ongoing revolution is the global map of marine gravity constructed from SEASAT altimeter data by Haxby [1987]. In fact, members of the marine geophysical community were, and, in some cases, still are, largely unaware of the spate of gravity field information coming from these satellites. Our purpose here is to help assure that this same community is aware of the very major increase in our knowledge of the marine gravity field which will come from GEOSAT, and that this increase will come on top of the gains made from SEASAT and Geos-3!