|Food dyes added to water on a rotating table represent water from different depths, to model how vortices form around seamounts. (Photo by Tom Kleindinst, WHOI Graphics Services)
|Physical Oceanographer Claudia Cenedese, left, with Rachel Bueno de Mesquita. (Photo by Tom Kleindinst, WHOI Graphics Services)
At first glance, it looks like an art project: a spinning Plexiglas box filled with paint. To Claudia
Cenedese, the box contains the oceanbut on a
A plastic mound in the center of the box represents a seamountan
extinct submarine volcanothat would span 1,500 kilometers
(930 miles) in the real ocean. Colored food dyes are injected
into the water from different locations on the “seamount”
(blue from the bottom, red from the middle, and green from
the top). The table rotates as the Earth does. A camera above,
rotating in synchrony with the table, photographs the swirling
field of small vortices that spin off the seamount. One large,
single vortex (green), however, forms above the seamount.
The same basic physical laws that govern geophysical fluid
dynamics in the box apply in the real ocean. In this experiment,
Cenedese (in blue, at right), an associate scientist in the
Physical Oceanography Department, and Rachel Bueno de Mesquita,
a visiting undergraduate from the University of Rome, explore
how seamounts sticking up from the seafloor modify ocean circulation
and create organized, rather than random, patterns of vorticity.
Such experiments reveal subtle complexities of ocean circulation.
They also help explain, for example, how larvae of animals
living on seamounts might spin out to colonize new seafloor
regions (as indicated by blue or purple dyes), or alternatively,
spin endlessly around the seamount and become trapped in one
region (as indicated by the green dye).
Theoreticians create mathematical equations with all
the interacting variables that go into complex geophysical fluid dynamics. Observationalists go to sea to observe actual ocean dynamics, but can observe only a tiny
portion of a wide-scale process. Somewhere in between
is Cenedese, an experimentalist, who devises laboratory
studies to observe and measure actual fluid dynamics on a small scale.