HR: 09:00h
AN: OS21D-05 INVITED     [Abstracts]
TI: Mapping Seafloor Tectonics from Space
AU: * Sandwell, D T
EM: dsandwell@ucsd.edu
AF: Scripps Inst. of Oceanography, 1102 IGPP, La Jolla, CA 92124-0225 United States
AU: Smith, W H
EM: Walter.HF.Smith@noaa.gov
AF: U.S. National Oceanic and Atmospheric Administration Laboratory for Satellite Altimetry, 1315 East West Hwy. Room 5408, Silver Spring, MD 20910-3282 United States
AB: Our current understanding of the topography and tectonics of the ocean basins is largely derived from dense satellite altimeter measurements of the marine gravity field combined with sparse geophysical measurements from research vessels. First generation satellite altimetry was initiated in the 1970s by NASA with the Skylab and GEOS-3 missions, followed by the brief but highly successful Seasat mission of 1978. Seasat provided the first global view of the marine gravity field, well illustrated by Bill Haxby's maps of the early 1980s. It is difficult to express the excitement in the scientific community when the global signatures of the postulated ridges, transforms, and subduction zones were revealed. Moreover, Seasat proved that non-repeat orbit altimetry was the obvious way to map the ocean basins and the US Navy quickly developed Geosat in 1985 to finish the job. For 10 years the Geosat data remained classified until ESA's ERS-1 duplicated the secret information. The sudden availability of dense measurements from these second generation altimeters (Geosat and ERS-1) is perhaps the most important ocean science observation in the last two decades. These data provided not only a spectacular confirmation of plate tectonics but also partly revealed smaller-scale structures including thousands of seamounts, propagating rifts, ridge jumps, and global-scale variations in seafloor roughness. In addition, the dense gravity information was combined with sparse ship soundings to construct global bathymetry maps at ~10 km resolution - a great improvement over hand-drawn maps but still far worse than our current maps of Mars, Venus, and the Moon. While these data filled a huge gap in our understanding of the ocean basins, they also triggered a thirst for more. Third generation altimeters with improved range precision are on the horizon. The scientific rationale for a factor of 5 improvement in altimeter precision spans three broad areas of earth science: one, resolving the fine-scale tectonic structure of the deep ocean floor (e.g., abyssal hills, microplates, propagating rifts, seamounts, meteorite impacts); two, measuring the roughness spectra of the seafloor on a global basis to better constrain models of tidal dissipation, vertical mixing, and mesoscale circulation of the oceans; and three, resolving the fine-scale gravity field for research, exploration and navigational needs. The views expressed here are solely the opinions of the authors and do not constitute a statement of policy, decision, or position on behalf of NOAA or the U. S. Government.
UR: http://topex.ucsd.edu/concept
DE: 1200 GEODESY AND GRAVITY
DE: 1640 Remote sensing (1855)
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 4275 Remote sensing and electromagnetic processes (0689, 2487, 3285, 4455, 6934)
DE: 4599 General or miscellaneous
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005