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| Titel |
On the advection of tracer by eddies on the beta-plane: A numerical study |
| VerfasserIn |
E. S. Benilov |
| 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 ; 6, no. 2 ; Nr. 6, no. 2, S.67-77 |
| Datensatznummer |
250003392
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| Publikation (Nr.) |
 copernicus.org/npg-6-67-1999.pdf |
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| Zusammenfassung |
| The evolution of tracer "injected" into an
equivalent barotropic eddy on the beta-plane is examined numerically. The eddy is governed
by the standard quasigeostrophic equation, and the concentration of tracer is governed by
the advection equation with diffusion. At the initial moment of time, the streamfunction
and distribution of tracer are both radially or elliptically symmetric. After the first
10-30 days, a spirallike strip, where the gradient of concentration is large, develops in
the tracer field, whereas the eddy remains smooth for a relatively long time. To put this
conclusion in quantitative terms, a "tracer variability indicator" is introduced
and shown to grow much faster than a similar characteristic of the potential vorticity
field (notwithstanding the fact that the tracer concentration and PV satisfy the same
governing equation). A simple explanation as to why the tracer is more affected by
filamentation than PV is provided for eddies with small Burger number. It is demonstrated
that the high-gradient strip develops, unless stopped by turbulent diffusion, into an
inversion (non-monotonicity) of the tracer concentration field. Finally, the results of
simulations are compared to the spiral patterns in the real-life eddies observed in the
East Australian Current. |
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