Data

Raw and processed data represent the value of gravity and height measurements.
Quad Geometrics

Data products of different types and formats are delivered, as listed here:

Station position

  • Station x,y positions based on GNSS and (offshore) underwater acoustic navigation. Offshore, this is usually provided by the ship and ROV operator.
  • Precise depth based on GNSS, InSar or traditional land surveying (onshore) or water pressure (offshore)
  • x,y,z-data are usually provided for all stations in an Excel spreadsheet.

Raw gravity

  • Gravity as output by the sensors. For Scintrex CG-5 or CG-6 this is gravity, tilt and temperature at 10 Hz or 6 Hz sampling. For absolute gravity it may be an average number.
  • Sensor tilt
  • Sensor temperature
  • Date and time
  • Station name – to connect with position
  • Metadata, dependent on type of measurement and survey
  • Calibration constants, from most recent calibrations

Raw pressure

  • Pressure proxy, for instance frequency output for Paroscientific Digiquartz sensors
  • Sensor temperature
  • Sensor tilt
  • Date and time
  • Station name – to connect with position

Raw reference pressure

  • Pressure proxy, for instance frequency output for Paroscientific Digiquartz
  • Sensor temperature
  • Sensor tilt
  • Date and time
  • Station name – to connect with position

Oceanographic data

  • From CTD probes, either launched from a ship crane or attached to the ROV:
  • Water temperature T(x,y,z,t)
  • Salinity s(x,y,z,t)

Weather data

  • Wave height (estimated from a weather buoy, a nearby oil platform, the ship movements or a shore station)
  • Air temperature
  • Wind (average and maximum speed, direction)
  • Rainfall (onshore)
  • Sunshine

Survey progress

  • Position of ship, ROV, car or instrument vs. survey time
  • Duration of instrument set-up and de-rigging at a site
  • Duration of measurements

Processed data

  • Station values of gravity, best estimate and probability distribution
  • Uncertainty of gravity values, with spatial dependencies
  • Station values of depth, best estimate and probability distribution
  • Uncertainty of depth values, with spatial dependencies