Enclosed please find an ERS SAR image of the Gulf of Oman containing
several spiral features. We have a SeaWiFs image coincident with this
SAR image which I am also sending. 

As you can see there is some nice correspondence between the two images.
The spirals are visible in the SAR as a result of biological matter on
the surface which forms into slicks when there are circulatory patterns
set up due to eddies. The slicks show up against the normal sea surface
background due to reduction in backscatter from the surface. The
biological content of the slicks causes the sea surface to become less
rough, hence providing less surface area to reflect back emitted radar
from the SAR sensor. The beauty of SAR is its all weather capability,
i.e. even when SeaWiFS is cloud covered, SAR will still give signals
back from the sea surface. Returns from the sea surface however are
affected by wind speed over the surface and this explains the large
black patches. The patches result from a drop in the wind at these
locations, leading to reduced roughness of the surface.

What we would be interested in is, how successful your SeaWiFS feature
(spiral) detection routines would be in highlighting the spirals in
this type of image, bearing in mind the other features and artefacts.
Maybe the wavelet transform could be employed in this context, as a form
of reducing the background signal to highlight the spirals.

Image courtesy of Will Aicken, DERA