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GCOS Ocean biogeochemistry ECV - Transient Tracers

Transient tracers are man-made chemical compounds released to the atmosphere at known quantities that can be used in the ocean to quantify ventilation, transit time distribution and transport time-scales. These compounds are all conservative in sea-water, or have well-defined decay-functions, and a well-established source function over time at the ocean surface. Measurement of transient tracers in the subsurface ocean thus provides information on the time-scales since the ocean was ventilated, i.e. in contact with the atmosphere. A combination of these tracers provide the means to constrain the transit time distribution (TTD) of a water-mass that allows inference of concentrations or fates of other transient compounds, such as anthropogenic carbon or nitrous oxide. Commonly measured transient tracers are the chlorofluorocarbons (CFCs) 11 and 12. More recently also the related compound sulfur hexafluoride (SF6) is regularly measured since it provides information on ventilation of the rapidly ventilated parts of the ocean. The radioactive isotopes 14C and tritium released during tests of nuclear bombs in the 1950s and 1960s have a known natural decay rate and are commonly used as transient tracers too.

Product Requirements:

  • Interior ocean CFC-12:
    • Frequency:  Annual to decadal
    • Resolution:  Every 20°
    • Required Measurement uncertainty:  ±1%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (in situ):  GOOS
  • Interior ocean CFC-11:
    • Frequency:  Annual to decadal
    • Resolution:  Every 20°
    • Required Measurement uncertainty:  ±1%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (in situ):  GOOS
  • Interior ocean SF6:
    • Frequency:  Annual to decadal
    • Resolution:  Every 20°
    • Required Measurement uncertainty):  ±1%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (in situ):  GOOS
  • Interior ocean tritium:
    • Frequency:  Annual to decadal
    • Resolution:  Every 20°
    • Required Measurement uncertainty:  ±0.5%, 0.005 TU
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (in situ):  GOOS
  • Interior ocean 3He:
    • Frequency:  Annual to decadal
    • Resolution:  Every 20°
    • Required Measurement uncertainty:  δ3He ±0.15%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (in situ):  GOOS
  • Interior ocean 14C:
    • Frequency:  Annual to decadal
    • Resolution:  Every 20°
    • Required Measurement uncertainty:  14C ±0.4%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (in situ):  GOOS
  • Interior ocean  39Ar:
    • Frequency:  Annual to decadal
    • Resolution:  Every 20°
    • Required Measurement uncertainty:  14C ±0.4%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (in situ):  GOOS

Networks:

Data Source: