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USGS CMG "Bathymetry" Definition

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This documents InfoBank's usage of bathymetry.
  • "Bathymetry" (as used within the CMG InfoBank) is the water depth relative to sea level.
  • Depth values may be either negative or positive, but should all be understood to be negative.
  • Elevations (topography) are the corresponding terminology for above sea level and are positive.
  • For InfoBank, the specification of "bathymetry" also contains "topography."
  • Depths are almost always derived indirectly by measuring the time required for a signal to travel from a transmitter, to the bottom, and back to a receiver.
  • This travel time is then converted to a depth based on a variety of estimations of the signal speed through the water column.
  • This may vary based on salinity, temperature, etc.
  • Unless specifically stated in the file, 1500 meters per second of time for a two-way (surface-->bottom-->surface) travel-time is commonly used.
Before you can walk on water, you've got to know where the rocks are.

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Page Last Modified: Mon Nov 4 03:37:26 PST 2013  (chd)