What data are available, and where can background information be found about the data processing?

Jaison Kruian contributed this note about data sources and an article discussing available data. (November 2006)

There is a recent article in Marine Geophysical Researches, by Marks and Smith on "An Evaluation of Publicly Available Global Bathymetry Grids" (see http://springerlink.metapress.com/content/w86v85v5u66g3841/?p=e22bda9684ef4291a7373478dba4b34bπ=2) (Volume 27, Number 1, 2006, DOI 10.1007/s11001-005-2095-4) which talks about Etopo2, GEBCO and few other datasets. This is an excellent article to read if you are interested in fine resolution bathymetry. Understanding how data is processed and put onto grids is important when choosing which data set to use.

Regarding the topography/coastline datasets, a number of high-resolution datastes are available. There are datasets like GEBCO, Etopo2 and GLOBE (only land elevation) which have resolutions of 1 Minutes, 2 Minutes and 1 Km respectively. Here is a list of freely available global datasets. As others become available, or if readers know of further sources, you are urged to contact the Ferret developers with that information at the Ferret "Contact Us" link.

Please note that the ocean topography or land elevation datasets can be used to create new coastline datasets (extracting lat & lon for zero depth/ elevation) but read the dataset documentation, especially about the data processing, to determine how reliable coastline data will be when derived like this.

List of free, Global, Ocean Topography/Land Elevation/Coastline/River datasets

Ocean Topography

• Dataset Name: Smith and Sandwell and Etopo2
• Resolution: 2 Minute
• Source: NOAA NGDC
• Data format: NetCDF
• On the Web
  • http://dss.ucar.edu/datasets/ds759.3/
  • http://ngdc.noaa.gov/mgg/fliers/06mgg01.html
  • http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html
  • http://ferret.pmel.noaa.gov/thredds/dodsC/data/PMEL/smith_sandwell_topo_v8_2.nc (DODS)
  • http://ferret.pmel.noaa.gov/LAS_docFiles/smith_sandwell_v8_2.html
  • http://www.ngdc.noaa.gov/mgg/fliers/97mgg03.html (poster)

• Dataset Name: Etopo5
• Resolution: 5 Minute
• Source: NOAA NGDC
• Data format: NetCDF
• On the Web
  • http://dss.ucar.edu/datasets/ds759.1
  • http://ingrid.ldeo.columbia.edu/SOURCES/.WORLDBATH/
  • http://ferret.pmel.noaa.gov/thredds/dodsC/data/PMEL/etopo5.nc (DODS)

• Dataset Name: General Bathymetric Chart of the Oceans (GEBCO)
• Resolution: 1 Minute
• Source: BODC
• Data Format: NetCDF (274 MB zip file)
• On the Web
  • http://www.bodc.ac.uk/data/online_delivery/gebco/
• Note: Though this dataset is 1 Minute resolution, it misses features which the lower-resolution ETOPO2 captures, due to over smoothing. See the following link for a comparison: http://www.vterrain.org/Elevation/Bathy/bathy_comp.html

Land Elevation

• Dataset Name: GLOBE
• Resolution: 1 Km, Gridded
• Source: NOAA NGDC
• Data format: NetCDF
• On the Web
  • http://iridl.ldeo.columbia.edu/SOURCES/.NOAA/.NGDC/.GLOBE/
  • http://www.ngdc.noaa.gov/mgg/topo/globe.html
• Note: Etopo2 and Etopo5 (see above) also have land elevation.

Ridge Bathymetry

• Dataset Name: Ridgembs Relational Database
• Resolution: Variable, can be as high as 50 m where data exists. No global coverage (wherever data is not available, Etopo2 is used as a regional background map).
• Source: Lamont-Doherty Earth Observatory (together with RIDGE & NSF)
• Data Format: NetCDF/ASCII
• On the Web
  • http://ocean-ridge.ldeo.columbia.edu/database/html/home.html
  • http://www.marine-geo.org/geomapapp/about.htm

Coastline/Shoreline Data

• Dataset Names:
  • NOAA/NOS Medium resolution coastline, 1:70,000
  • World Vector Shoreline, 1:250,000
  • World Data Bank II, 1:2,000,000
  • World Coast Line, 1:5,000,000
• Resolution: .....
• Data Format: ASCII
• Source: NOAA NGDC
• On the Web
  • http://rimmer.ngdc.noaa.gov/mgg/coast/getcoast.html
  • http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html (home)
• Note: There is a Ferret FAQ about "Detailed Coastlines and Borders" at http://ferret.pmel.noaa.gov/Ferret/FAQ/graphics/coastlines.html which describes how to use the data from this source for drawing borders in Ferret.

Political/International/Internal Boundaries

• Dataset Names:
  • World Data Bank II Political boundaries
  • World Data Bank II International Boundaries
  • World Data Bank II Internal Boundaries
  • World Vector Shoreline & All political boundaries
• Resolution: .....
• Data Format: ASCII
• Source: NOAA NGDC
• On the Web:
  
  • http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html (home)

Rivers

• Dataset Name: World Data Bank II Rivers
• Resolution: .....
• Data Format: ASCII
• Source: NOAA NGDC
• On the Web
  
  • http://www.ngdc.noaa.gov/mgg/shorelines/shorelines.html (home)
• Note: Again see the Ferret FAQ about "Detailed Coastlines and Borders" at http://ferret.pmel.noaa.gov/Ferret/FAQ/graphics/coastlines.html which describes how to use the data from this source for drawing rivers in Ferret.

Where to look for more information?

• http://ioc.unesco.org/oceanteacher/OceanTeacher2/06_OcDtaMgtProc/05_DtaAnal&Prods/08_SelectProds/SelAnalProds.htm
• http://www.vterrain.org/Elevation/Bathy/index.html
• http://topex.ucsd.edu/marine_topo/text/topo.html

You can also check:

• http://topex.ucsd.edu/WWW_html/srtm30_plus.html
• http://fermi.jhuapl.edu/abyss/documents/HOTSWG3.3.pdf
• http://www.gcc.ntu.edu.tw/modelsplanning/database/gcrc_databank/datamanage/DISasia/igbp-dis/activity_summary/summary_act1_8.html

More about Etopo2

• CleanTOPO2: CleanTOPO2 is a touched up and generalized version of SRTM30 Plus, a public domain dataset that combines sea floor and land elevation data of the entire world. On the Web: http://www.shadedrelief.com/cleantopo

General Notes about sites listed above

• With dss.ucar and bodc.ac.uk you have to create an account (it is free) in order to download datasets. While creating account with bodc.ac.uk, keep the final page where the verification code is to be pasted as it is, and wait for a mail from bodc. Once you get the mail copy and paste the verification code into the box provided.
• Citations for above datasets are available/mentioned in the respective web pages.
  Names marked as (DODS) can be accessed via DODS, using Ferret, e.g.
  

    yes? USE "http://ferret.pmel.noaa.gov/thredds/dodsC/data/PMEL/smith_sandwell_topo.nc"