Asymmetric impact of Central Pacific ENSO on the reduction of tropical cyclone genesis frequency over the western North Pacific since the late 1990s

Tropical cyclone (TC) genesis frequency over the western North Pacific (WNP) is significantly reduced since the late 1990s, coinciding with a Pacific decadal oscillation (PDO) phase transition from positive to negative. In this study, the underlying mechanism for this change is investigated through...

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Bibliographic Details
Published in:Climate dynamics 2020-01, Vol.54 (1-2), p.661-673
Main Authors: Kim, Han-Kyoung, Seo, Kyong-Hwan, Yeh, Sang-Wook, Kang, Nam-Young, Moon, Byung-Kwon
Format: Article
Language:English
Subjects:
Asymmetry
Climate cycles
Climate models
Climatology
Computer simulation
Cyclones
Earth and Environmental Science
Earth Sciences
El Nino
El Nino events
El Nino phenomena
El Nino-Southern Oscillation event
Geophysics/Geodesy
Hurricanes
La Nina
La Nina events
Ocean currents
Oceanography
Pacific Decadal Oscillation
Phase transitions
Planetary waves
Properties
Properties (attributes)
Reduction
Rossby waves
South Korea
Southern Oscillation
Storms
Tropical climate
Tropical cyclones
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Summary:Tropical cyclone (TC) genesis frequency over the western North Pacific (WNP) is significantly reduced since the late 1990s, coinciding with a Pacific decadal oscillation (PDO) phase transition from positive to negative. In this study, the underlying mechanism for this change is investigated through analysis of asymmetric central Pacific (CP) El Niño-Southern Oscillation (ENSO) properties induced by the negative PDO phase. Our results suggest that the significant reduction is caused by asymmetric CP ENSO properties, in which the CP La Niña is more frequent than the CP El Niño during negative PDO phases; furthermore, stronger CP La Niña occurs during a negative PDO phase than during a positive PDO phase. CP La Niña (El Niño) events generate an anticyclonic (cyclonic) Rossby wave response over the eastern WNP, leading to a significant decrease (increase) in eastern WNP TC genesis. Therefore, more frequent CP La Niña events and the less frequent CP El Niño events reduce the eastern WNP mean TC genesis frequency during a negative PDO phase. In addition, stronger CP La Niña events during a negative PDO phase reinforce the reduction in eastern WNP TC genesis. The dependency of CP ENSO properties on the PDO phase is confirmed using a long-term climate model simulation, which supports our observational results. Our results will also improve understanding of TC in other basins, since both PDO and CP ENSO variability influence global dynamics.
ISSN:0930-7575
1432-0894
DOI:10.1007/s00382-019-05020-8