Posted by Mathijs Schouten on May 17, 2001 at 02:02:33:
First, I'd like to congratulate you on this very
interesting "poster". It's a simple way of showing
a lot.
I have one question about the Natal pulses or large
disturbances that are clearly visible in your movie.
Is the total flow increasing before these disturbances
occur? I'm asking that because an hypothesis for the
generation of these pulses, is the passing by of eddies
from the north. Large eddies occur in the Mozambique
Channel, which travel southward on the outer edge of
the Agulhas current every now and then. At least on one
occasion, we have seen an eddy like that triggering a
Natal pulse.
It is happening on pictures of the region just south
of Natal during april/may 2000, available at
www.phys.uu.nl/~schouten/natalpulse.jpg
(sorry for the poor size and quality, but I hope it's
still visible). Four snapshots of sst, of which the
first one shows an eddy interacting with the Agulhas
(we know that, as a drifter had been circling the eddy
for six weeks, then left into the current). On the
subsequent three snpshots the pulse is growing and
traveling south.
So could this have happened also during your mooring
year? I guess it could, as also northward velocities
on the outside of the current (150-200km) are observed
in your movie (eg. day 170). But when an eddy is lying
on the outside of the current, their combined transport
should increase and probably also be concentrated further
towards the coast. Especially the latter I don't see
in the movie.
Best regards,
Mathijs.