In:
Journal of Physical Oceanography, American Meteorological Society, Vol. 41, No. 9 ( 2011-09-01), p. 1683-1693
Abstract:
Eddies off the Strait of Luzon (termed here as “Leddies,” analogous to “Teddies” originating from the Indonesian Throughflow) are formed rapidly and migrate swiftly. Their migration rate (~10–20 cm s−1) is an order of magnitude faster than that of most eddies of the same scale (~1 cm s−1). On the basis of observations, it has been suggested earlier that the rapid generation process is due to the southeast monsoon. Here, the authors place this earlier suggestion on a more solid ground by developing both analytical and process-oriented numerical models. Because the eddies are formed by the injection of foreign, lighter Kuroshio water into the South China Sea (SCS), the eddies are modeled as lenses: that is, “bullets” that completely encapsulate the mass anomaly associated with them. It turns out that the rings migrate at an angle α (between 0° and 90°) to the right of the wind direction {i.e., tan−1[(2 − γ)f2R/8g′CD, where in conventional notation γ is the vorticity, R the eddy radius, and CD the interfacial friction coefficient along the lower interface of the lens}. Their fast migration speed is given by 2(τS/ρW)(sinα)/fH, where τS is the wind stress on the surface, ρw the water density, and H is the maximum eddy depth. With high interfacial drag (i.e., large CD), the rings move relatively slowly (but still a lot faster than Rossby waves) in the wind direction, whereas with low drag they move fast at 90° to the right. These analytically predicted values are in good agreement with isopycnic numerical simulations.
Type of Medium:
Online Resource
ISSN:
0022-3670
,
1520-0485
DOI:
10.1175/2011JPO4530.1
Language:
English
Publisher:
American Meteorological Society
Publication Date:
2011
detail.hit.zdb_id:
2042184-9
detail.hit.zdb_id:
184162-2
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