Distribution of the p CO 2 in surface seawater of the western and central equatorial Pacific during the 1986/87 El Niño/Southern oscillation event

Measurements of the partial pressure of CO 2 in surface seawater ( p CO 2 ) of the central and western equatorial Pacific were made in January and February 1987, with the main objective of studying variations in CO 2 exchange between the air and the sea during the El Niño/Southern Oscillation (ENSO) event. In January 1987, the western equatorial Pacific had p CO 2 distributions similar to those during non‐ENSO periods, despite the fact that large variations in p CO 2 had occurred during the 1982/83 ENSO event. The p CO 2 along 180° and 160°E was fairly constant (336.7 µatm to 355.7 µatm), while along 160°W it varied remarkably (342.8 µatm to 409.4 µatm). A maximum appeared near the equator, and the p CO 2 was quite high from 3°N to 5°S (365.7 µatm to 409.4 µatm). In January and February 1987, the p CO 2 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 CO 2 between the sea and air, compared to the 1982/83 ENSO event.