Japan Geoscience Union Meeting 2025

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[E] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG43] Multi-scale ocean-atmosphere interaction in the tropics

Wed. May 28, 2025 1:45 PM - 3:15 PM Exhibition Hall Special Setting (6) (Exhibition Hall 7&8, Makuhari Messe)

convener:Yukiko Imada(Atmosphere and Ocean Research Institute, the University of Tokyo), Ayako Seiki(Japan Agency for Marine-Earth Science and Technology), Takanori Horii(Japan Agency for Marine-Earth Science and Technology), Youichi Kamae(Faculty of Life and Environmental Sciences, University of Tsukuba), Chairperson:Ayako Seiki(Japan Agency for Marine-Earth Science and Technology), Youichi Kamae(Faculty of Life and Environmental Sciences, University of Tsukuba)

2:15 PM - 2:30 PM

[ACG43-03] La Niña Modoki and diversity of coastal El Niño events

*Tomoya Noguchi1, Tomoki Tozuka1 (1.The University of Tokyo)


Keywords:coastal El Niño, La Niña Modoki, equatorial Pacific

Coastal El Niño events are associated with anomalously warm sea surface temperatures along the coast of South America and can cause flood damage in the coastal areas. While understanding their mechanisms is crucial, past research has mostly focused on individual events, without identifying their general characteristics. This study classifies coastal El Niño events into two types based on whether they develop into basin-scale El Niño and examines why some coastal El Niño events develop and decay locally, without evolving into basin-scale El Niño events. Observational data analysis reveals that coastal El Niño events that occur under a La Niña Modoki condition do not develop into basin-scale El Niño. This may be attributed to equatorial upwelling Kelvin waves induced by easterly wind anomalies to the west of negative SST anomalies that eventually reach the South American coast. Sensitivity experiments using a regional ocean model further support this finding.