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Ocean Colour: Essential climate variables

Ocean colour remote sensing primarily aims to derive the spectrum of marine surface reflectance from satellite observations. In turn, marine reflectance can be used to determine inherent optical properties (absorption and back-scattering coefficients) and concentrations of optically significant constituents present in the upper layer of the ocean.

Among these is the concentration of chlorophyll-a, a photosynthetic pigment found in phytoplankton cells. Ocean colour remote sensing is thus the only satellite remote sensing technique that opens a window onto ocean biology.



Considering the various products that can be derived from marine reflectance data as well as the role of marine phytoplankton in the carbon cycle (responsible for approximately half of the Earth's total carbon fixation), the Global Climate Observation System lists both the spectrum of marine reflectance and the chlorophyll-a concentration as Essential Climate Variables (ECV).

In the context of the Copernicus programme, the JRC aims to maintain and develop a climate-quality database of ocean-colour-derived products from the suite of relevant satellite missions. This involves developing advanced climate data records, determining their uncertainties, and devising approaches to combine data from various missions, with the final objective of constructing and analysing a consistent data series that is suitable for climate research. Eventually, these climate data records can help to study the dynamics of the marine ecosystems or compute primary production with the JRC primary productivity model.


Mélin, F., and V. Vantrepotte: How optically diverse is the coastal ocean? Remote Sens. Environ., 160, 235-251, 10.1016/j.rse.2015.01.023, 2015.

Mélin, F. and B.A. Franz. Assessment of satellite ocean colour radiometry and derived geophysical products, in Optical Radiometry for Oceans Climate Measurements, chap. 6.1, G. Zibordi, C. Donlon, A. Parr, eds., Elsevier Physical Science Series, 609-638, 2014.


Frédéric Mélin