Spirals on the sea
In: Scientia Marina (Barcelona). Consejo Superior de Investigaciones Científicas. Institut de Ciènces del Mar: Barcelona. ISSN 0214-8358; e-ISSN 1886-8134, more
Also appears in:Gili, J.-M.; Pretus, J.L.; Packard, T.T. (Ed.) (2001). A Marine Science Odyssey into the 21st Century. Scientia Marina (Barcelona), 65(S2). Institut de Ciències del Mar: Barcelona. 326 pp. https://dx.doi.org/10.3989/scimar.2001.65s2, more
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| Keyword |
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| Author keywords |
Remote sensing, air-sea boundary, frontal formation, mixing |
| Abstract |
Spiral eddies were first seen in the sun glitter on the Apollo Mission 30 years ago; they have since been recorded on SAR missions and in the infrared. The spirals are globally distributed, 10-25 km in size and overwhelmingly cyclonic. They have not been explained. Under light winds favorable to visualization, linear surface features with high surfactant density and low surface roughness are of common occurrence. We have proposed that frontal formations concentrate the ambient shear and prevailing surfactants. Horizontal shear instabilities ensue when the shear becomes comparable to the coriolis frequency. The resulting vortices wind the liner features into spirals. The hypothesis needs to be tested by prolonged measurements and surface truth. Spiral eddies are a manifestation of a sub-mesoscale oceanography associated with upper ocean stirring; dimensional considerations suggest a horizontal diffusivity of order 103 m2 s-1. |
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