A sea surface height perspective on El Niño diversity, ocean energetics and energy damping rates
- 1Physical Oceanography Laboratory/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- 2College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao, China
- 3Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA
- 4LOCEAN/IPSL, Sorbonne University, Paris, France
- 5Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York, USA
Ocean energetics is a useful framework for understanding El Niño development and diversity; however, its key element, available potential energy (APE), requires accurate ocean subsurface data that are hard to measure. However, sea surface heights (SSH) provide a useful alternative. In this study, we describe an SSH-based index, SSHI, that accurately captures APE variations and can be easily computed from satellite observations. Using SSHI we obtain an observation-based estimate of the APE damping timescale α-1 of approximately 1.7 years, slightly longer than previous ocean reanalysis-based estimates. We further show that SSHI records the relative strength of the thermocline feedback, serving as an indicator for El Niño “flavors”. SSHI demonstrates a clear decadal shift in El Niño-Southern Oscillation (ENSO) properties that occurred in early 2000s, with a more tilted mean thermocline and weaker thermocline slope variations indicative of the dominance of “Central Pacific” El Niño activity during the past two decades.
How to cite: Shi, J., Fedorov, A., and Hu, S.: A sea surface height perspective on El Niño diversity, ocean energetics and energy damping rates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4086, https://doi.org/10.5194/egusphere-egu2020-4086, 2020
