Quantity Description (monthly means) Units

 chl-a Sea surface chlorophyll-a concentration mg.m-3

 par Photosynthetically available radiation Einstein m-2.day-1

 Kd490 Diffuse attenuation coefficient m-1

 pp Net primary productivity of carbon g C m-2.day-1

 aph Absorption Coefficient of Phytoplankton at 443nm m-1

 adg Absorption Coefficient of detritus/CDOM at 443nm m-1

 bbp Particulate backscatter Coefficient at 443 nm m-1

 zeu Surface Productive Layer m
Bio-optical variables
Photosynthetically Active Radiation (PAR)
PAR is defined as the quantum energy flux from the sun in the spectral range 400 to 700 nm, usable in the process of photosynthesis by phytoplankton, benthic algae and seagrass. It is expressed in Einstein m-2 day-1 (where 1 Einstein is equivalent to the energy of 1 mole of photons of monochromatic light).

Diffuse Attenuation Coefficient (Kd490)
The diffuse attenuation coefficient Kd490 indicates the transparency of the water column in the green part of the spectrum (ca. 490 nm). It is a standard product from satellite ocean colour radiometry that results from the combined action of absorption and backscattering by the water constituents, and also depends on the structure of the surrounding light field.

Surface productive layer (zeu)
The surface productive layer or euphotic zone represents the upper part of the water column that is illuminated by the sun down to the 1% light level. It is a surface layer where most of the primary production occurs.
Biological (biotic) variables
Chlorophyll is a photosynthetic pigment commonly present in all phytoplankton species. It is used as a proxy for phytoplankton biomass. Chlorophyll concentration is a standard product from satellite-based optical sensors, usually retrieved from empirical algorithms using reflectance ratios at two or more wavebands.

Water column primary production (PP)
The primary production represents the amount of organic carbon produced through phytoplankton photosynthesis. It is a critical element of the Earth's carbon budget and the marine food web. The depth-integrated primary production is modeled from the satellite-based phytoplankton biomass concentration and PAR.

Absorption Coefficient of Phytoplankton at 443nm (aph)
The absorption coefficient aph (m-1) represents the fraction of incident light absorbed by phytoplankton organisms. It is an index of variability of the phytoplankton biomass in marine and coastal turbid waters.

Absorption Coefficient of colored detrital matter at 443nm (adg)
The absorption coefficient adg (m-1) represents the fraction of incident light absorbed by both detrital particles and colored dissolved organic matter (CDOM). Dissolved organic matter is an important component of the oceanic carbon cycle. It is also used as proxy to assess the impact of terrigenous inputs in coastal waters.

Particulate matter (particulate backscatter coefficient at 443 nm, bbp)
The backscatter coefficient bbp (m-1) represents the fraction of incident light that is scattered backward from its original path. The backscattering coefficient gives a good indication of the concentration of suspended organic and inorganic particles (e.g. sediments) in the water.

More information are available from the Data discovery tool (sensors, time serie, view, download, WMS, WCS, metadata):