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| Two-Way Interactions Between Equatorially-Trapped Waves and the Barotropic Flow |
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Citation： |
James FERGUSON,Boualem KHOUIDER,Maryam NAMAZI.Two-Way Interactions Between Equatorially-Trapped Waves and the Barotropic Flow[J].Chinese Annals of Mathematics B,2009,30(5):539~568 |
| Page view： 2184
Net amount： 1457 |
Authors： |
James FERGUSON; Boualem KHOUIDER; Maryam NAMAZI; |
Foundation： |
by the Natural Sciences and Engineering Research Council of Canada (No.
288339-2004) and the Canadian Foundation for Climate and Atmospheric Sciences (No. GR-7021). |
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| Abstract： |
Lateral energy exchange between the tropics and the midlatitudes is a topic
of great importance for understanding Earth’s climate system. In this paper, the authors
address this issue in an idealized set up through simple shallow water models for the in-
teractions between equatorially trapped waves and the barotropic mode, which supports
Rossby waves that propagate poleward and can excite midlatitude teleconnection patterns.
It is found here that the interactions between a Kelvin wave and a fixed meridional shear
(mimicking the jet stream) generates a non-trivial meridional velocity and meridional con-
vergence in phase with the upward motion that can attain a maximum of about 50%,
which oscillates on frequencies ranging from one day to 10 days. When, on the other hand,
the barotropic flow is forced by slowly propagating Kelvin waves a complex flow pattern
emerges; it consists of a phase-locked barotropic response that is equatorially trapped and
that propagates eastward with the forcing Kelvin wave and a certain number of planetary
Rossby waves that propagate westward and toward the poles as seen in nature. It is sug-
gested here that the poleward propagating waves are to some sort of multi-way resonant
interaction with the phase locked response. Moreover, it is shown here that a numeri-
cal scheme with dispersion properties that depend on the direction perpendicular to the
direction of propagation, namely the 2D central scheme of Nessyahu and Tadmor, can
artificially alter significantly the topology of the wave fields and thus should be avoided in
climate models. |
Keywords： |
Equatorially trapped waves, Wave interactions, Jet stream, Rossby waves,
Phase locked, Dispersion relation, Central scheme, Climate modeling |
Classification： |
65M06, 65M12, 76B15, 76B55, 76B60, 86A10 |
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