FY 1987

Evaporative cooling of the western equatorial Pacific Ocean by anomalous winds

Meyers, G., J.R. Donguy, and R.K. Reed

Nature, 323(6088), 523–526, doi: 10.1038/323523a0 (1986)

Global climate anomalies during El Niño/Southern Oscillation (ENSO) episodes are controlled by anomalous patterns of sea surface temperature (SST) in the equatorial Pacific Ocean. Many studies during the past decade have indicated that warming of the eastern Pacific is caused by advection and downwelling associated with anomalous eastward currents. Cooling of the western Pacific is probably not caused by an analogous process because zonal temperature gradients are small west of the dateline. We have searched for an explanation of the cooling because relatively small temperature changes in the west can be important in influencing the atmospheric general circulation. Here we compare oceanic heat storage observed by expendable bathythermographs during 1979-83 with local processes in the heat budget, including various surface fluxes and mixing. The results show that cooling during 1982-83 was caused by evaporation due to anomalous meridional wind. The anomalous wind field in the region had been noted earlier by Harrison.