The Satellite Geodesy research group at the Cecil H. and Ida M. Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego applies laser, microwave, and gravity methods to aid in solving specific geophysical problems, such as modeling the Earth's gravitational field, active tectonics (such as faulting), and terrestrial and oceanic topography.
The Satellite Geodesy group gathers and maintains data on the global seafloor topography from:
- Global Topography - measured from ship depth soundings and estimated seafloor topography
- Radar Altimetry - marine gravity from satellite altimetry
- Synthetic Aperture Radar - crustal strain and topography from synthetic aperture radar interferometry
The SRTM30 Plus project (aka Global Predicted Bathymetry project) is a data fusion of SRTM land topography with measured and estimated seafloor topography
The SRTM30 Plus data was was first published in 2004. The eleventh and most recently published release was published November 19 2014.
References:
Smith, W H F, and D T Sandwell, Global seafloor topography from satellite altimetry and ship depth soundings, Science, v 77, p1957-1962, 26 September 1997.
Becker, J J, D T Sandwell, W H F Smith, J Braud, B Binder, J Depner, D Fabre, J Factor, S Ingalls, S-H Kim, R Ladner, K Marks, S Nelson, A Pharaoh, R Trimmer, J Von Rosenberg, G.Wallace, P Weatherall, Global Bathymetry and Elevation Data at 30 Arc Seconds Resolution: SRTM30_PLUS, Marine Geodesy, 32:4, 355-371, 2009.
Data: SIO, NOAA, US Navy, NGA, GEBCO
People involved in the published research and data include::
- NOAA STAR << nice video
- Google Scholar
- ResearchGate
Co-author of the Generic Mapping Tools
Smith, W H F, and D T Sandwell, Global seafloor topography from satellite altimetry and ship depth soundings, Science, v 77, p1957-1962, 26 September 1997.
This is the paper that initiated the SRTM 30 Plus project.
Science magazine, Vol 227, 26 September 1997 pp 1956-162
A digital bathymetric map of the oceans with a horizontal resolution of 1 to 12 kilometers was derived by combining available depth soundings with high-resolution marine gravity information from the Geosat and ERS-1 spacecraft. Previous global bathymetric maps lacked features such as the 1600-kilometer-long Foundation Seamounts chain in the South Pacific. This map shows relations among the distributions of depth, sea floor area, and sea floor age that do not fit the predictions of deterministic models of subsidence due to lithosphere cooling but may be explained by a stochastic model in which randomly distributed reheating events warm the lithosphere and raise the ocean floor.
Becker, J J, D T Sandwell, W H F Smith, J Braud, B Binder, J Depner, D Fabre, J Factor, S Ingalls, S-H Kim, R Ladner, K Marks, S Nelson, A Pharaoh, R Trimmer, J Von Rosenberg, G.Wallace, P Weatherall, Global Bathymetry and Elevation Data at 30 Arc Seconds Resolution: SRTM30_PLUS, Marine Geodesy, 32:4, 355-371, 2009.
http://topex.ucsd.edu/sandwell/publications/124_MG_Becker.pdf
A new 30-arc second resolution global topography/bathymetry grid (SRTM30 PLUS) has been developed from a wide variety of data sources. Land and ice topography comes from the SRTM30 and ICESat topography, respectively. Ocean bathymetry is based on a new satellite-gravity model where the gravity-to-topography ratio is calibrated using 298 million edited soundings. The main contribution of this study is the compilation and editing of the raw soundings, which come from NOAA, individual scientists, SIO, NGA, JAMSTEC, IFREMER, GEBCO, and NAVOCEANO. The gridded bathymetry is available for ftp download in the same format as the 33 tiles of SRTM30 topography. There are 33 matching tiles of source identification number to convey the provenance of every grid cell. The raw sounding data, converted to a simple common format, are also available for ftp download.
The following ftp directory at UCSD provides access to many interesting papers and other material
ftp://topex.ucsd.edu/pub/
ftp://topex.ucsd.edu/pub/sandwell/NGA_proposal/ONR_proposal_9.pdf
Marine gravity and bathymetry are foundational data, providing basic infrastructure for military, scientific, economic, educational, and political work. Naval operations require accurate gravity models for inertial navigation and fire control, and accurate bathymetry to assess navigational hazards in uncharted areas. In addition, coastal bathymetry is used for improving models of tides and currents. Over the next 3 to 5 years, a wealth of new marine gravity data will be provided by three currently operating satellite altimeters CryoSat, Jason-1, and Envisat. With careful processing of the new data, in combination existing altimetry and bathymetry data we propose to:
- Improve global marine gravity maps by a factor of 2 in deep ocean areas and a factor of 4 in the Arctic areas and on shallow continental margins.
- Use these improved gravity maps along with our global compilation of soundings to refine a 30-arcsecond bathymetry model (SRTM30_PLUS).
- Prepare the next generation of scientists for ocean research. We will coordinate our research efforts with the Defense Mapping Agency, the Naval Oceanographic Office, and make these grids available to Navy labs, defense contractors, and the general public.
topex.ucsd.edu/marine_topo/text/topo.html 1996
We are constructing a complete bathymetric map of the oceans at a 3-10 km resolution by combining all of the available depth soundings collected over the past 30 years with high resolution marine gravity information provided by the Geosat, ERS-1/2, and Topex/Poseidon altimeters. Detailed bathymetry is essential for understanding physical oceanography and marine geophysics. Currents and tides are controlled by the overall shapes of the ocean basins as well as the smaller sharp ocean ridges and seamounts. Because erosion rates are low in the deep oceans, detailed bathymetry reveals the mantle convection patterns, the plate boundaries, the cooling/subsidence of the oceanic lithosphere, the oceanic plateaus, and the distribution of off-ridge volcanoes. Current global digital bathymetry maps (e.g. ETOPO-5) lack many important details such as a 400 km-long ridge that rises to within 135 m of sea level. Moreover, they are contaminated by long-wavelength errors (~2000 km) which prevent accurate identification of seafloor swells associated with mantle plumes [Smith, 1993].
The elevation data used here was obtained from the 'topo30' file of 1,866,240,000 bytes dated November 6, 2014 downloaded from:
ftp://topex.ucsd.edu/pub/srtm30_plus/topo30/
From the Read Me:
The subdirectory called topo30 has the data stored in a single large file of 2-byte integers in MSB format (i.e. big-endian). The grid spans 0 to 360 in longitude and -90 to 90 in latitude. The upper left corner of the upper left grid cell has latitude 90 and longitude 0. There are 43200 columns and 21600 rows. A matching source identification file (SID) called topo30_sid is also included. The sid numbers are stored as unsigned 2-byte integers.
The following files are included as part of the SRTM30 Plus source files:
Read Me V11
References SRTM Plus
Copyright notice
General Attribution ( Microsoft Word file)