4:15 PM - 4:30 PM
[ACG33-09] Energy flux streamfunction and potential of interannual waves in the tropical Pacific Ocean
Keywords:Downwelling and upwelling Kelvin waves, Rossby waves, Energy transfer routes/episodes
This study examines how upper ocean waves associated with El Niño and La Niña events play a role in the interaction between the western, central, and eastern parts of the ocean basin from the perspective of energy circulation. Recent studies have made it possible to trace wave energy circulation paths as if tracing group velocity vectors and without any barriers between equatorial and mid-latitude dynamics. Note that it was not obvious to trace or quantify the generation, transmission, and dissipation of disturbances in a chain simply by displaying the distribution of these energy flux vectors on a map. To solve this problem, this study proposes a method to apply the Helmholtz decomposition to the energy flux distribution and analyze the time series of the maxima and minima of the stream function and potential components, respectively. This time series has the meaning that the energy flux is integrated across its path, and its time variation can be compared with the Niño 3 index. In making this comparison, we note that the energy fluxes in this study show eastward transfer events both during El Niño and La Niña events and cannot distinguish between downwelling and upwelling Kelvin waves. On the other hand, the Niño 3 index, which represents climatic anomalies in water temperature over the eastern equatorial Pacific, can distinguish between downwelling and upwelling Kelvin waves, yet its quantitative meaning reflects only the physical component related to potential energy, and the physical component related to kinetic energy is not factored in. In this study, we present a solution to these problems and provide valuable validation using the outputs of 51 years of numerical simulations.