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| Titel |
A simple nonlinear model of low frequency (interseasonal) oscillations in the tropical atmosphere |
| VerfasserIn |
D. Luo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 3, no. 1 ; Nr. 3, no. 1, S.29-40 |
| Datensatznummer |
250000701
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| Publikation (Nr.) |
 copernicus.org/npg-3-29-1996.pdf |
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| Zusammenfassung |
| In this paper, for a prescribed
normalized vertical
convective heating profile, nonlinear Kelvin wave
equations
with wave-CISK heating over equatorial region is
reduced to a
sixth-order nonlinear ordinary differential equation
by using
the Galerkin spectral method in the case of
considering
nonlinear interaction between first and second
baroclinic
modes. Some numerical calculations are made with the
fourth-
order Rung-Kutta scheme. It is found that in a narrow
range of
the heating intensity parameter b, 30-60-day
oscillation can
occur through linear coupling between first and
second
baroclinic Kelvin wave-CISK modes for zonal
wave-number one
when the convective heating is confined to the
lower and
middle tropospheres. While for zonal wavenumber two,
30-60-day
oscillation can be observed in a narrow range of b
only when
the convective heating is confined to the lower
troposphere.
However, in a wider range of this heating intensity
parameter,
30-60-day oscillation can occur through nonlinear
interaction
between the first and second baroclinic Kelvin wave-CISK modes
with zonal wavenumber one for three vertical
convective
heating profiles having a maximum in the upper,
middle and
lower tropospheres, and the total streamfield of the
nonlinear
first and second baroclinic Kelvin wave-CISK modes
possesses a
phase reversal between the upper- and lower-tropospheric wind
fields. While for zonal wavenumber two, no
30-60-day
oscillations can be found. Therefore, it appears
that
nonlinear interaction between vertical Kelvin wave-CISK
modes favours the occurrence of 30-60-day oscillations,
particularly,
the importance of the vertical distribution of
convective
heating is re-emphasised. |
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