Continuous measurements of the partial pressure of CO2 (pCO2) in air and surface seawater are performed with GASPAR, an autonomous equipment designed by the Instituto de Investigaciones Mariñas, IIM-CSIC, Vigo), according to Körtzinger system (Körtzinger et al., 1996). Atmospheric CO2 is measured by the system from an air intake mounted in the mast of the ship and surface seawater is drawn from the ship's uncontaminated seawater supply and it is bifurcated to pass through the equilibrator, combination of the bubble type (Takahashi, 1961) and the laminar flow type (Poisson et al., 1993), and through the thermosalinometer, oximeter and fluorometer, consecutively.

CO2 and CO2 measurements were performed with a Li-COR non-dispersive infrared analyser, the best experimental approach to assess pCO2 of an air-flushing equilibrator (DOE, 1994).The equipment is calibrated with two standards, CO2-free air and high CO2 standard gas.

CO2 is corrected for the temperature shift between in-situ temperature and equilibrator temperature using an empirical equation (DOE, 1994) which was originally proposed by Takahashi et al. (1993).

Wind speed and direction are recorded from an anemometer mounted at the top of foremast, at 35 meter height above the sea level.

Sensor references: LICOR model 6262 infrared CO2/H2O, GPS KODEN KGP 913, Thermosalinometer model SBE-45-MicroTSG, Oxymeter model SBE-43, Fluorometer WETLabs, Meteorologic station receptor Aanderaa Dataloger 3634, Wind speed sensor Aanderaa 2740, Wind direction sensor Aanderaa 3590.