Measurements of the partial pressure of CO2 in surface seawater (pCO2) of the central and western equatorial Pacific were made in January and February 1987, with the main objective of studying variations in CO2 exchange between the air and the sea during the El Ni¿o/Southern Oscillation (ENSO) event.

In January 1987, the western equatorial Pacific had pCO2 distributions similar to those during non-ENSO periods, despite the fact that large variations in pCO2 had occurred during the 1982/83 ENSO event.

The pCO2 along 180¿ and 160¿E was fairly constant (336.7 &mgr;atm to 355.7 &mgr;atm), while along 160¿W it varied remarkably (342.8 &mgr;atm to 409.4 &mgr;atm). A maximum appeared near the equator, and the pCO2 was quite high from 3¿N to 5¿S (365.7 &mgr;atm to 409.4 &mgr;atm).

In January and February 1987, the pCO2 in the surface seawater of the central equatorial Pacific was disturbed due to the ENSO event, but there seems to have been a net positive exchange of CO2 between the sea and air, compared to the 1982/83 ENSO event. ¿ American Geophysical Union 1988