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Photosynthetically Available Radiation

A Photosynthetically Available Radiation (PAR) sensor is used to measure the spectral range of light that is available in the water column for use by primary producers for photosynthesis (400-700 nanometers). Essentially, PAR sensors provide a measure of the amount of light available for photosynthesis and how that varies over time and depth in the water column. Chlorophyll, the most abundant plant pigment in land plants and in ocean phytoplankton, is most efficient at capturing red and blue light.

Data Products

This instrument measures the following data products. Select a data product's name to learn more.

The algorithm code used to generate this instrument's data products is also available in the ion-functions GitHub repository.

Instrument Models & Deployed Locations

The OOI includes the following instrument makes and models for this instrument type. Follow the links below to find out where in the OOI this instrument has been deployed. You'll also find quick links for each instrument to Data portal, where you can plot and access data.

Series Make Model
PARADA Satlantic digital PAR
PARADK Biospherical Instruments QSP-2200
PARADM Biospherical Instruments QSP-2155
PARADN Biospherical Instruments QSP-2150

The Sea-Bird ECO-PAR™ sensor provides highly accurate measurements of PAR (400–700 nm) in all aquatic environments. Photo credit:

Primary Science Discipline

Biospherical QSP PAR sensors are designed to measure scalar irradiance with a PAR response in natural waters to depths of up to 2,000 m. Photo credit: