Nitrogen is an essential element for plant growth in the ocean, and the dominant labile inorganic form is nitrate. Nutrients typically have higher concentrations in the deep ocean; concentrations near the surface are often very low due to uptake by phytoplankton during photosynthesis. The nitrate vertical gradient may be very dynamic, responding to both physical and biological processes. The OOI Nitrate sensors optically measure the amount of nitrate (NO3-) dissolved in seawater by examining its absorption of ultraviolet (UV) light. The Sea-Bird SUNA V2 (Submersible Ultraviolet Nitrate Analyzer) is a chemical-free UV nitrate sensor based on the ISUS (In Situ Ultraviolet Spectroscopy) UV nitrate measurement technology developed at MBARI. These optical sensors provide fast response measurements, allowing for the sensor to be deployed on profilers, gliders, and AUVs.

Data Products

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

Data Product Code DPS
Nitrate Concentration NITROPT

The algorithm code used to generate data products for this instrument 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.

Class-Series Make Model
NUTNRA Satlantic Deep SUNA
NUTNRJ Satlantic SUNA V2
NUTNRM Satlantic SUNA V2
NUTNRN Satlantic Deep SUNA

Primary Science Discipline


Research Themes

Access Data

NUTNR on the Data Portal