Observed dispersion relation of mixed Rossby gravity waves and 17-day tropical instability waves in the Pacific Ocean

Mixed Rossby-Gravity waves (often referred to as Yanai waves) play an important role in a variety of phenomena in the tropical ocean and atmosphere. Using sea surface height (SSH) data derived from recent satellite observations, we present the observed dispersion relationship of Yanai waves in the Pacific Ocean. A wavenumber-frequency spectral analysis of SSH fields shows prominent spectral peaks along the dispersion curves of first and second baroclinic mode oceanic Yanai waves. Also, salient features of tropical instability waves (TIWs) with a period of ~17 days can be effectively isolated based on a cross-correlation analysis of sea surface temperature (SST) and SSH time series that are filtered in wavenumber-frequency domain. The results are consistent with the analysis of TOGA TAO data along 140W.