Decadal Variation of the Surface Water PCO[sub2] in theWestern and Central Equatorial Pacific.

The equatorial Pacific Ocean is one of the most imporant yet highly variable oceanic source areas for atmospheric carbon dioxide (CO[sub2]). Here, we used the partial pressure of CO[sub2] (PCO[sub2]), measured in surface waters from 1979 through early 2001, to examine the effect on the equatorial Pacific CO[sub2] chemistry of the Pacific Decadal Oscillation phase shift, which occurred around 1988 to 1992. During the decade before the shift, the surface water PCO[sub2] (corrected for temperature changes and atmospheric CO[sub2] uptake) in the central and western equatorial Pacific decreased at a mean rate of about -20 µatm per decade, whereas after the shift, it increased at about +15 µatm per decade. These changes altered the CO[sub2] sink and source flux of the equatorial Pacific significantly. [ABSTRACT FROM AUTHOR]