The PAR sensor (Photosynthetic Active Radiation) measures the radiation from that part of the light spectrum (400 - 700 nm) that organisms can use for photosynthesis. This involves comparing the amount of sunlight diffusing through the water column with the light at the surface using Li-Cor sensors. The EXO PAR allows an insight into photoinhibition, primary productivity, algal blooms and eutrophication.
The sensor can also be used for long-term monitoring under conditions of high pollution and biofouling thanks to a wiper system.