FY 1995

fCO₂ distributions in the eastern equatorial Pacific during and after the 1992–93 El Niño

Feely, R.A., R. Wanninkhof, C.E. Cosca, H. Chen, M. Steckley, and P.P. Murphy

In Global Fluxes of Carbon and Its Related Substances in the Coastal Sea-Ocean-Atmosphere System, Proceedings of the 1994 Sapporo IGBP Symposium, Sapporo, Japan, 14–17 November 1994, 360–367 (1995)

As part of the U.S. JGOFS Equatorial Pacific Process Study, measurements of fCO were determined for the atmosphere and in the surface waters of the central and eastern equatorial Pacific during the spring and autumn of 1992 and 1993, and the spring of 1994 after the 1992-93 ENSO event. Surface water fCO data indicate significant differences between the springtime El Niño conditions and the autumn post-El Niño conditions. The autumn fugacity (fCO) maxima were approximately 15-55 µatm higher than in the spring. The lower surface fCO values in the spring data set were the result of: (1) advection of CO-depleted water from the west at the equator near 170°W; and (2) reduced upwelling and lower fCO distributions as consequence of lighter zonal winds in the eastern Pacific from 140°W to 110°W. In the spring of 1993 elevated sea surface temperatures were observed in the eastern Pacific but the fCO levels were about 25-40 µatm higher than those observed in spring of 1992. In spring of 1994 sea surface temperatures were near the climatological mean and fCO levels were 70-90 atm higher than the 1992 levels. These results clearly indicate that the largest sustained fCO variations in the eastern Equatorial Pacific occur during ENSO events.