Posted by Ronald Souza on May 25, 2001 at 08:33:20:
In Reply to: Re: drifter eddy measurements posted by Olaf Boebel on May 15, 2001 at 02:27:24:
Dear Olaf and Toby Garfield,
I am very pleased with your comments and suggestions and I'll read very carefully through the literatureyou have already published.
I have passed my eyes through some references on the AIW in the SW Atlantic in the past (Boebel et al's JGR 104(C9), for instance, is supperb!) but I was a bit concerned on relating my results to the subsurface. I might rethink my results and I'll be pleased to include Boebel's data in my figure 4.
Following Toby's advice on taking care when using Lagrangian data to descripe eddy sizes, I must add that of course the paper is limited but, when other in situ measurements are lacking, remote sensing data may be used to assess eddies sizes. What I did was to compare the their sizes as measured by the two complementary data sets to see what would result.
As I explore better in my PhD thesis (http://www.soton.ac.uk/~rbds/projtes.html), my drifting buoys were found to be concentrated in the region of the greater horizontal temperature gradients at surface in the convergence region. Although cloud coverage did not allow much, I have also spotted the detachment of eddies from the main currents and also coincidences in sizes between these eddies and their signatures in the images (for a time window of +/- 20 days between the center of the trajectories and the image's acquisition time).
The suggestion is that the surface buoys were traveling along the gradients when the eddies were spinned off the meanders and, by consequence, they were kept outside the eddies along their external surface boundary with the adjacent waters.
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Eddies belonging to class 1 (the small ones) are incliding the tidal and inertia-generated ones. I have explored some of these concepts when trying todescroibe a costal, northward surface current present during wintertie off the southern coast of Braszil up to about 25oS (details in http://www.soton.ac.uk/~rbds/projtes.html - the Brazilian Costal Current). I however apperciate Toby's suggestion to implement Sanderson's (1995) technique.
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I will try also to make the drifting buoys animation a little better and try to include some wind data to observe their effect on the current reversals in the cost of Brazil.
Cheers, thanks, Ronald