An Ocean Resonance in the Southeast Pacific

Satellite Altimeter observations of sea surface height show an extensive region of high variability in the Southeastern Pacific which previous studies have suggested is a Rossby wave trapped by topography. Here we investigate the feature using results from a high‐resolution global ocean model. We calculate the empirical orthogonal modes and find that 29% of the SSH variability is due to a single mode. We correlate the time series of the mode with the local Ekman pumping and find that the correlation is largest when the wind curl is averaged over a region roughly the size of the mode. We calculate the response function relating the two time series and find that it is dominated by a resonance at zero frequency with a decay time of about two days. We conclude that the feature is a highly damped geostrophic mode of the ocean.