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Abstract. The North Brazil Current Rings (NBCR) penetration into the Caribbean Sea is being investigated by employing a merged altimeter-derived sea height anomaly (TOPEX/Poseidon, Jason-1 and ERS-1, 2), the ocean surface color data (SeaWiFS) and Global Drifter Program information. Four strategies are being applied to process the data: (1) calculations of the Okubo-Weiss parameter for NBCR identification, (2) longitude-time plots (also known as Hovmöller diagrams), (3) two-dimensional Radon transforms and (4) two-dimensional Fourier transforms.A twofold NBCR structure has been detected in the region under investigation. The results have shown that NBC rings mainly propagate into the Caribbean Sea along two principal pathways (near 12 • N and 17 • N) in the ring translation corridor. Thus, rings following the southern pathway in the fallwinter period can enter through very shallow southern straits as non-coherent structures. A different behavior is observed near the northern pathway (∼17 • N), where NBC rings are thought to have a coherent structure during their squeezing into the eastern Caribbean, i.e. conserving the principal characteristics of the incident rings. We attribute this difference in the rings' behavior to the vertical scales of the rings and to the bottom topography features in the vicinity of the Lesser Antilles.

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In this article, we study the dynamic response of a soap film under continuous electromagnetic forcing. The dynamics presented here describe the forcing of a monopole vortex during its generation at the center of the film. This response is quantified by the dimensionless Reynolds and Chandrasekhar numbers. When Chandrasekhar number reaches values near 800, Reynolds number reaches a damping rate. An analysis of the kinetic energy throughout the film shows that its response can be explained by Gibbs and Marangoni elasticity. Upon small forcing, the film shows an fast response after which it maintains its initial speed at all times (Marangoni). For a large forcing however, the speed of the film increases continuously throughout the experiment (Gibbs).

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