Equatorial Wave Reflection and Equatorial Warm Water Volume

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Fundamental to the dynamics and prediction of El Niño and the Southern Oscillation (ENSO) is the variability of the equatorial Pacific warm water volume (WWV). Variations in this WWV both lead and lag major ENSO indices by several months and recent research suggests that the reflection of low-frequency ocean energy at the eastern and western Pacific Ocean boundaries plays a fundamental role in the dynamics of the WWV mode. But the reflection at the eastern Pacific Ocean boundary, particularly the decay of the El Niño signal along the boundary south of the equator, is not understood. This decay greatly reduces the energy that reaches the western boundary from the eastern boundary and should profoundly affect the amplitude of the equatorial WWV. This work's main goal is to observe and understand the interannual flow near the eastern tropical Pacific boundary. Satellite altimeter and coastal tide gauge data will be used to document and understand the tropical eastern Pacific interannual coastal flow. In particular, theory and satellite-estimated eddy variability will be used to test whether the alongshore behavior of the interannual coastal signal, especially its decay south of 5S, can be explained by energy loss due to eddies which are known to originate near the boundary. As part of the analysis the dynamics of the low-frequency observed equatorial currents will be elucidated and, in the eastern Pacific, their possible utility in predicting ENSO will be examined.Broader impactsOver the years the PI has incorporated his research results on ENSO in his course work and books and he plans to continue this activity in this project. He will also mentor a female junior scientist in conducting research and writing scientific papers. Achievement of the goals in this proposal will lead to increased understanding of ENSO which greatly influences agriculture, water resources, fisheries, the number of hurricanes and wildfires, energy needs for heating/cooling and the prevalence of famine and disease in certain regions.