Air–sea CO2 flux variability in the equatorial Pacific Ocean near 100°W

The interannual variability of the CO 2 partial pressure ( p CO 2oc ) in the surface layer of the east equatorial Pacific Ocean near 100°W is studied and compared with the sea surface temperature (SST) monitored from satellites. This variability is shown to be correlated with the SST anomaly rather than with the temperature itself. The p CO 2oc variability is related to the variability of the upwelling systems (the equatorial upwelling and the upwelling along the American coast), the main influence being from the coastal upwelling via the surface water advected from the east. A method is derived to interpolate the p CO 2oc measurements using the SST satellite measurements. By combining the result with the exchange coefficient ( K ) deduced from the wind speed provided by satellite borne instruments we deduce the air–sea CO 2 flux and for the 1st time we monitor continuously its temporal evolution. The variability of this flux is mainly due to the variability of K , with a clear seasonal variation. The flux obtained using the Liss and Merlivat (1986) relationship averaged from April 1985 to June 1997 in the region 97.5°−107.5°W 0–5°S is 1.67 mole m −2 yr −1 of CO 2 leaving the ocean with an estimated accuracy of 30%. DOI: 10.1034/j.1600-0889.1999.t01-1-00013.x