The large-scale context for the TOGA Coupled Ocean-Atmosphere Response Experiment

Summary The TOGA Coupled Ocean-Atmosphere Response Experiment (COARE) concentrated a variety of observational systems in the warm pool of the western equatorial Pacific for an Intensive Observation Period (IOP) November 1992 through February 1993. In this paper, aspects of the largescale variations of the tropical atmosphere and Pacific Ocean surrounding the observations of air-sea interaction in the Intensive Flux Array (IFA) during the IOP are described, with the objective of providing a context for the future analyses of these observations.The evolution of the 1991–1992 El Niño/Southern Oscillation event was unusual: Warm SST anomalies in the equatorial cold tongue region switched to colder than climatology in the last half of 1992, but waters warmer than 30°C remained displaced eastward just west of the dateline, coninuing to fuel anomalous convection there during the IOP. Fortunately, SST in the IFA remained warmer than 29°C during most of the IOP, and convective activity was observed over the IFA. The Southern Oscillation Index, which had relaxed to near zero prior to the experiment, decreased during the IOP, reflecting sea level presure changes associated with renewed westerly wind activity. In response to these westerly wind events, the warm pool migrated back into the central equatorial Pacific, leading to a reintensification of the ENSO warm SST anomalies east of the dateline.With 10 Figures