Air-sea CO2 flux variability in the equatorial Pacific Ocean near 100 degrees W

The interannual variability of the CO2 partial pressure (pCO(2oc)) in the s urface layer of the east equatorial Pacific Ocean near 100 degrees W is stu died and compared with the sea surface temperature (SST) monitored from sat ellites. This variability is shown to be correlated with the SST anomaly ra ther than with the temperature itself. The pCO(2oc) variability is related to the variability of the upwelling systems (the equatorial upwelling and t he upwelling along the American coast), the main influence being from the c oastal upwelling via the surface water advected from the east. A method is derived to interpolate the pCO(2oc) measurements using the SST satellite me asurements. By combining the result with the exchange coefficient (K) deduc ed from the wind speed provided by satellite borne instruments we deduce th e air-sea CO2 flux and for the Ist rime we monitor continuously its tempora l 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 degrees-107.5 degrees W 0-5 degrees S is 1.67 mole m(-2) yr(-1) of CO2 leaving the ocean with an estimated accuracy of 30%.