Observations of El Niño-Southern Oscillation induced Rossby waves in the northeast Pacific using in situ data

Bathythermometric observations from standard National Oceanographic Data Center data sets are used to show evidence of Rossby waves in the northeast Pacific Ocean following several E1 Nino-Southern Oscillation events between 1968 and 1991. Observations of a westward propagating warm anomaly following the 1982-1983 El Nino are consistent with evidence from ocean models and satellite observations that coastally trapped Kelvin waves of tropical origin excite Rossby waves in the northeast Pacific. Observed Rossby wave phase speeds are about 1.6 cm s -1 higher than those predicted by linear shallow-water theory. At midlatitudes, observed waves are more than 1.5 times faster than theory. Phase speeds of Rossby waves in a 1/8° resolution nonlinear primitive equation model exceed standard linear theory, but only by about 0.1 cm s -1 , despite the fact that the model should replicate mechanisms that have recently been proposed to explain the observed anomalously fast phase speeds.