Role of nonlinear western boundary reflections during the onset of the 2014 and 2015 El Niño events
Abstract
Ocean observations at the Pacific entrance of the Indonesian seas are used to study the role of the western boundary reflection in the evolution of the 2014 and 2015 El Niño events. The TAO mooring observations over the equatorial Pacific Ocean suggested outbursts of westerly wind events (WWE) in early 2014 and 2015. Upwelling Kelvin waves were observed to propagate to the east during the relaxation of the WWE. Satellite altimeter data have shown the propagation of upwelling Rossby waves to the western boundary forced by these WWE. The connection of the Rossby and Kelvin waves are suggested by significant reversals of moored current meter flows within the thermocline in the Maluku Channel in the springs of 2014 and 2015, which are associated with significant changes of the Mindanao Current at the forcing of the upwelling equatorial Rossby waves. The resulting upwelling Kelvin waves emitted from the western Pacific during relaxations of the WWE are strong enough to halt the progress of the 2014 El Niño but too weak to interrupt the development of the 2015 El Niño. The results suggest the importance of nonlinear western boundary reflections in the onset and development of El Niño. New mooring measurements in the eastern Indonesian seas will be retrieved in the upcoming cruise. The variability of the ocean current in the eastern Indonesian seas during the development of the 2016 La Niña will also be discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMOS12A..08Y
- Keywords:
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- 4215 Climate and interannual variability;
- OCEANOGRAPHY: GENERALDE: 4522 ENSO;
- OCEANOGRAPHY: PHYSICALDE: 4532 General circulation;
- OCEANOGRAPHY: PHYSICALDE: 4556 Sea level: variations and mean;
- OCEANOGRAPHY: PHYSICAL