When the research vessel Kronprins Haakon was built in 2016, a new automatic CO2 measurement system was installed (General Oceanics system). The system consists of an equilibrator, which sea water is pumped through at flow of about 3L/min. The seawater enters the equilibrator through a spiral nozzle, which forms a regular spray, thus, the water and the gas phase achieve equilibriums fast. The gas phase is then pumped through a Non-Dispersive Infrared (NDIR) detector, where the mole fraction of carbon dioxide is measured. From this, the fugacity of CO2 (fCO2) is calculated by using the respective sea surface temperature and salinity. Regularly, the system also measures four reference gases and atmospheric CO2 fugacity. Besides the fCO2, also sea surface temperature, sea surface salinity, and dissolve oxygen in the sea surface are measured using a thermosalinograph (SBE21) and an Aanderaa Oxygen Optode, respectively. The water intake is at 4 m depth.