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GCOS Ocean Biogeochemistry ECV - Ocean Color

Ocean colour is measured as the ocean colour radiance (OCR). OCR is the wavelength-dependent solar energy captured by an optical sensor looking down at the sea surface. These water-leaving radiances contain information on the ocean albedo and information on the constituents of the seawater, in particular, phytoplankton pigments such as chlorophyll-a. Data analysis is not easy as satellite measurements also include radiation scattered by the atmosphere and the ocean surface. The relatively weak OCR signal is some 5%–15% of the strength of the incident solar radiation. OCR products are used to assess ocean ecosystem health and productivity, and the role of the oceans in the global carbon cycle, to manage living marine resources, and to quantify the impacts of climate variability and change. OCR products, in particular chlorophyll-a, are also required by the modelling community for the validation of climate models, and for use in data-assimilation systems for reanalysis and initializing forecasts.

Product Requirements:

  • Water Leaving Radiance:
    • Frequency:  Daily
    • Resolution:  4 km
    • Required Measurement uncertainty:  5% (blue & green wavelengths)
    • Stability (per decade unless otherwise specified):  0.50%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (Satellite):  WGClimate
  • Chlorophyll-a Concentration:
    • Frequency:  Weekly averages
    • Resolution:  4 km
    • Required Measurement uncertainty:  30%
    • Stability (per decade unless otherwise specified):  3%
    • Standards/References:  See http://www.ioccp.org/index.php/foo
    • Entity (Satellite):  WGClimate

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