The Large-Scale Context for the TOGA Coupled Ocean-Atmosphere Response Experiment

Roger Lukas
Department of Oceanography and
University of Hawaii
1000 Pope Rd
Honolulu HI 96822
USA

Peter J. Webster
Program in Atmospheric and Oceanic Sciences
University of Colorado
Boulder, Colorado

Ming Ji
National Weather Service
National Oceanic and Atmospheric Administration
Suitland, Maryland

Ants Leetmaa
National Weather Service
National Oceanic and Atmospheric Administration
Suitland, Maryland


Abstract
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 large-scale 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 1991-92 El Nino/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 30C remained displaced eastward just west of the dateline, continuing to fuel anomalous convection there during the IOP (Figure 2; Figure3; Figure 4). Fortunately, SST in the IFA remained warmer than 29C during most of the IOP, and convective activity was observed over the IFA (Figure 5). The Southern Oscillation Index (Figure 6), which had relaxed to near zero prior to the experiment, decreased during the IOP, reflecting sea level pressure 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.


Reference:

Lukas, R., P. Webster, M. Ji, A. Leetmaa, 1995: The Large-Scale Context for the TOGA Coupled Ocean-Atmosphere Response Experiment. Meteorology and Atmospheric Physics, Vol. 56, pp. 3-16.


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Last modified: November 3, 1997