Giant ocean frisbee rotate off the coast of Brazil

Addition.

March 21, 2011. Researchers from the University of Miami found that Brazilian whirlpools and more rapidly than previously thought.

When the North Brazil Current (PBTs) moves northward along the northeastern coast of Brazil, it captures the water of the South Equatorial Current and the freshwater Amazon, becoming a source of warm, nutrient-rich, water. To the north-west part of Brazil's SBT abruptly turns to the right and flows eastward along the equator. Sometimes, especially at the turn is a sharp angle, and then the thread is twisted into a loop and breaks away from the mainstream — the original premise of warm water. This system is moving to the north-west, rotating clockwise, moving across the ocean like a frisbee in the air.

 

Of these eddies has learned a few decades ago, but did not have accurate data on their basic parameters, such as size, speed and rotation, the depth of the rotation. Based on measurements by airborne and stationary tools, researchers from the University of Miami Guillermo Gastelo and Bill Jones described the parameters of ten whirlpools, surveyed from 1998 to 2000. The study's authors believe that the eddies can be considered as solid masses of water, rotating clockwise and surrounded by a belt of water at a slower rate, which prevents eddies from external influences.

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In addition, the study showed that the eddies in the SBT is actually bigger, faster and have more depth than the previous observations have shown.

The work, entitled "The surface structure of eddies in the North Brazil Current, obtained onboard and towed Doppler profilers," is published in the "Journal of Geophysical Research — Oceans," the publication of the American Geophysical Union.

Translation: Vitaly Semkin
Source: University of Miami

Summary of the article "The surface structure of whirlpools in the North Brazil Current, obtained onboard and towed Doppler profilers"

January 20, 2011. Bending the North Brazil Current in western tropical Atlantic at times creates a similar system anticyclones, which are then moved to the north-west. Between 1998 and 2000, a study of a large number of whirlpools SBT with onboard and towed Doppler profilers. This paper analyzes the options ten rotating systems with emphasis on the dynamic parameters of the sea surface. Whirlpools different radial structure, consisting of two systems: the inner region rotates almost like a solid body, the external system is exponentially fading to the periphery. Observations have revealed a sharp transition between the vortex processes in the transition between systems, and the presence of a strong vortex of opposite direction, surrounding the inner core. It is shown that the Gaussian model, usually used to describe the surface structure of these eddies are suitable for the determination of sea surface height anomaly, but it is extremely well suited to the evaluation of other parameters, such as maximum speed. Therefore, we propose a new two-tier model, which gives an improved approximation of the radial structure. According to the approximation tsiklogeostroficheskogo balance, distribution of surface elevation of the internal system has a parabolic shape, while the outer ring has an exponential structure resembling the velocity field. Interestingly, the intensity of many of the observed eddies close to the theoretical limit for anticyclones in these latitudes, which is apparently associated with inertial instability.

Translation: Vitaly Semkin
Source: JOURNAL OF GEOPHYSICAL RESEARCH

Source: vseneprostotak.ru.

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