On Nuka Arctica, the first automatic CO2 measurement system was installed in 2004. In 2014 a completely new system was installed to ensure stable and high quality measurements during the next years. The system consists of an equilibrator, through which seawater is pumped with a flow of about 3L/min. A spiral nozzle forms a regular spray, so that the water and the gas phase achieve equilibriums fast. The gas phase is then pumped through a NDIR analyzer, there the mole fraction of carbon dioxide is measured. From this, the fCO2 is calculated by using the respective sea surface temperature and salinity. In a regular rhythm the system switches to measure four different calibrations gases and the atmospheric CO2 fugacity. Besides the fugacity of carbon dioxide, also the sea surface temperature and the sea surface salinity is measured. The sea surface salinity and measured by LOCEAN using a SBE21. This data can be found here.