Observed Dispersion Relation of Yanai Waves and 17-Day Tropical Instability Waves in the Pacific Ocean

Abstract

Using sea surface height (SSH) data derived from recent satellite observations, we present the observed dispersion relationship of mixed Rossby Gravity (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. These statistical repre sentations of oceanic Yanai waves and TIWs are important for the evaluation of numerical model simulations of these waves and for improving our understanding of the physics of 17-day TIWs.