El Ninño and La Ninña - Equatorial Pacific thermocline depth and sea surface temperature anomalies, 1986-98

Simple models of the El Ninño-Southern Oscillation (ENSO) phenomenon have provided many of our basic ideas about ENSO mechanisms. These models exhibit a range of correlation patterns between thermocline depth anomaly (Z₂₀A) and sea surface temperature anomaly (SSTA). We use 13 years of Pacific equatorial waveguide observations to explore the relationships between Z₂₀A and SSTA. We find significant correlation in the eastern pacific, and in the east-central pacific when the east-central Pacific is normal or cooler than normal. We find no correlation in the western, west-central and east-central (when warmer than normal) Pacific. It is inappropriate to attribute SSTA changes to Z₂₀A changes. Coupled ENSO models should be reexamined in light of these observed Z₂₀A/SSTA relationship. Analysis of ocean general circulation models suggests that progress in understanding ENSO may depend as mush on understanding SSTA/wind/near-surface current relationships and processes, as upon thermocline change processes.