Low-Frequency Modulation of Intraseasonal Equatorial Kelvin Wave Activity in the Pacific from SODA: 1958–2001

Intraseasonal equatorial Kelvin wave activity (IEKW) at a low frequency in the Pacific is investigated using the Simple Ocean Data Assimilation (SODA) oceanic reanalyses. A vertical and horizontal mode decomposition of SODA variability allows estimation of the Kelvin wave amplitude according to the...

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Bibliographic Details
Published in:Journal of climate 2008-11, Vol.21 (22), p.6060-6069
Main Authors: Dewitte, Boris, Purca, Sara, Illig, Serena, Renault, Lionel, Giese, Benjamin S.
Format: Article
Language:English
Subjects:
Amplitude
Atmospheric models
Atmospherics
Climate change
Climate models
Climate variability
Data assimilation
Data collection
Dynamics of the ocean (upper and deep oceans)
Earth Sciences
Earth, ocean, space
El Nino
Exact sciences and technology
External geophysics
Frequency analysis
General circulation models
Kelvin waves
Marine
Meteorology
Ocean currents
Oceans
Physics of the oceans
Power lines
Remote sensing
Sciences of the Universe
Sea level
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Summary:Intraseasonal equatorial Kelvin wave activity (IEKW) at a low frequency in the Pacific is investigated using the Simple Ocean Data Assimilation (SODA) oceanic reanalyses. A vertical and horizontal mode decomposition of SODA variability allows estimation of the Kelvin wave amplitude according to the most energetic baroclinic modes. A wavenumber–frequency analysis is then performed on the time series to derive indices of modulation of the IEKW at various frequency bands. The results indicate that the IEKW activity undergoes a significant modulation that projects onto baroclinic modes and is not related in a straightforward manner to the low-frequency climate variability in the Pacific. Linear model experiments corroborate that part of the modulation of the IEKW is tightly linked to change in oceanic mean state rather than to the low-frequency change of atmospheric equatorial variability.
ISSN:0894-8755
1520-0442
DOI:10.1175/2008JCLI2277.1