caa a22 4500 605474303 CHVBK 20210128100347.0 cr unu---uuuuu 210128e20150101xx s 000 0 eng 10.1007/s00382-014-2354-7 doi (NATIONALLICENCE)springer-10.1007/s00382-014-2354-7 Processes in the Pacific La Niña onset triggered by the Atlantic Niño [Elektronische Daten] [Irene Polo, Marta Martin-Rey, Belen Rodriguez-Fonseca, Fred Kucharski, Carlos Mechoso] Previous observational and model studies have shown that a warm (cold) event in the equatorial Atlantic during the boreal summer are related to the development of a Pacific La Niña (El Niño) event, that is fully developed in the following winter. Although the connection takes place via atmospheric bridge, the processes at work have not been clarified for such a remote and lagged relationship. The present paper uses a partially coupled atmosphere-ocean model to infer a mechanism by which a Pacific El Niño event can be developed. In this way, enhanced equatorial convection in the equatorial Atlantic during a warm event results in enhanced subsidence and surface wind divergence over the equatorial Pacific around the dateline. This wind anomaly contributes to pile up water in the western equatorial Pacific, triggering a perturbation in the depth of the oceanic thermocline, which propagates eastward as an equatorial Kelvin wave from autumn to winter. The thermocline shallowing as the wave propagates allows for cooling of the oceanic mixed layer through anomalous temperature advection by anomalous zonal currents and by mean vertical entrainment velocity. Zonal advective and thermocline feedbacks reinforce the surface winds anomalies over the central eastern equatorial Pacific setting up the conditions for the development of a cold event in this ocean. The sequence during an Atlantic cold event is similar with the appropriate change in signs. These findings are relevant to ENSO predictability at seasonal timescales. Springer-Verlag Berlin Heidelberg, 2014 El Niño-Southern Oscillation (ENSO) nationallicence Atlantic Niño nationallicence Kelvin wave nationallicence Walker circulation nationallicence Polo Irene NCAS-Climate, Department of Meteorology, University of Reading, Earley Gate, P.O. Box 243, RG6 6BB, Reading, UK aut Martin-Rey Marta Meteorology and Geophysics Department, Universidad Complutense de Madrid (UCM), Plaza de las Ciencias, 28040, Madrid, Spain aut Rodriguez-Fonseca Belen Meteorology and Geophysics Department, Universidad Complutense de Madrid (UCM), Plaza de las Ciencias, 28040, Madrid, Spain aut Kucharski Fred The Abdus Salam International Centre for Theoretical Physics, P.O. Box 586, 34100, Trieste, Italy aut Mechoso Carlos Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles (UCLA), 7127 Math Sciences Building 405 Hilgard Avenue, Los Angeles, CA, USA aut Climate Dynamics Springer Berlin Heidelberg 44/1-2(2015-01-01), 115-131 0930-7575 44:1-2<115 2015 44 382 https://doi.org/10.1007/s00382-014-2354-7 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-014-2354-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Polo Irene NCAS-Climate, Department of Meteorology, University of Reading, Earley Gate, P.O. Box 243, RG6 6BB, Reading, UK aut NATIONALLICENCE 700 1- Martin-Rey Marta Meteorology and Geophysics Department, Universidad Complutense de Madrid (UCM), Plaza de las Ciencias, 28040, Madrid, Spain aut NATIONALLICENCE 700 1- Rodriguez-Fonseca Belen Meteorology and Geophysics Department, Universidad Complutense de Madrid (UCM), Plaza de las Ciencias, 28040, Madrid, Spain aut NATIONALLICENCE 700 1- Kucharski Fred The Abdus Salam International Centre for Theoretical Physics, P.O. Box 586, 34100, Trieste, Italy aut NATIONALLICENCE 700 1- Mechoso Carlos Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles (UCLA), 7127 Math Sciences Building 405 Hilgard Avenue, Los Angeles, CA, USA aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 44/1-2(2015-01-01), 115-131 0930-7575 44:1-2<115 2015 44 382