Aldo P. Solari wrote:

> Nice  question.  All  of  the 7 Canary Islands [1] have their own
> pair  of clockwise and anti-clockwise eddies. These are generated
> by  the Canary current coming from North --> water masses collide
> on  the northern shore and accelerate (due to a Venturi effects)
> while turning around the islands. These mesoscalar structures are
> "seen"  from  outer  space  through  infra  red, radar and color
> scanner  imagery.  Also,  between  the  eddies,  there are the so
> called  "shadow"  zones  where  water  exchange  is  low/minimal,
> temperature  rises from approx. 16-18ºC to 24 (year around): they
> are huge nurseries of marine organisms.

This seems to imply that your eddies are relatively stable.  Of course I
might be reading things into your statements that are not there, but this is
an interesting idea.  Here on the E. Coast of Florida, we have more than our
share of interaction with eddies.  The Gulf Stream throws more than it's
share of them off.  Ours are not stable and currents can vary from nothing
to ripping from one day to the next, sometimes from one hour to the next.
Charter fishing boats track them via satellite imaging.  As far as I know,
the dive boats don't track them, but I could be wrong.  It's not all that
unusual for us to have to select an alternative site due to eddy currents.

> From  the  biological  point  of view, the clockwise eddy is more
> interesting  since  it concentrates plankton as well as the whole
> of the trophic chain.
>
> Also,  the  anti-clockwise  eddy  is  interesting, as well, as it
> "throws"  away  plankton  due  to centrifugal forces; these become
> "glued"  to  the  ocean  front  "wall" (water masses of different
> temperature).

You left me behind on this one.  Why would a clockwise eddy concentrate
plankton while an anti clockwise one threw it off (due to centripetal
acceleration rather than centrifugal force)?  In my experience (big on
numbers, low on details), eddy currents are usually circular.  I would
expect them to concentrate internally and scatter externally regardless of
direction of rotation.

Lee