München 2019 – scientific programme

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UP: Fachverband Umweltphysik

UP 9: Hydrology, oceanography and miscellaneous

UP 9.2: Invited Talk

Thursday, March 21, 2019, 14:30–15:00, HS 22

El Niño's little brother in the tropical Atlantic - mechanisms and impacts — •Joke Lübbecke — GEOMAR Helmholtz Centre for Ocean Research Kiel

A climate mode similar to the Pacific El Niño - Southern Oscillation (ENSO) exists in the tropical Atlantic Ocean. Sea surface temperature (SST) anomalies associated with this Atlantic Niño mode can have substantial impacts on rainfall over western Africa and northeastern South America as well as the marine ecosystem along the African coast.

Various processes have been suggested to contribute to the generation of Atlantic Niño events. In addition to the dominant Bjerknes feedback - which links the SST anomalies in the eastern equatorial basin to western basin wind stress anomalies and equatorial thermocline tilt - meridional advection of temperature anomalies, Rossby waves reflecting into equatorial Kelvin waves, and net surface heat flux can play an important role for individual events.

The strength and symmetry of the Atlantic Bjerknes feedback elements vary between decades. Consequently the characteristics of the Atlantic Niño, such as its spatial pattern and amplitude, and its impacts are not stationarity in time. The multi-decadal modulations might be related to the phase of the Atlantic multidecadal oscillation (AMO).