From Gilles Reverdin: reve@locean-ipsl.upmc.fr

Dear Yi,

I tried to post an email through the blog, but I am clearly a lost cause...
too old to work in this world...

these are very nice simulations, that illustrate the large diversity
of trajectories that we will get, I am sure. This is also consistent
with intuition and past experience,
that we should focus during Strasse with Augustdeployments of the 10
SVPS+10 SVP drifters
relatively to the west (36W, lets say in this 150 km box), in order
for the drifters to be complementary, with the late Spetember Spurs
cruise deployments near 38°W.
We will have the flexibility of the additional 5 SVPS + 5 SVP
drifters near the end of the Strasse cruise (near September 10),
but depending of time, a good part of those might be deployed in a batch.

   Cheers, Gilles.

From: rick.lumpkin@noaa.gov

Hi Yi,

Thanks for running these.  I also ran your interactive tool on the SPURS site, as I was surprised at how there seems to be a dividing line between ~20N and ~21N south of which the drifters go south and quickly leave the domain, while just to the N they move N a bit before heading W.  The statistical runs don't do that, but both the dynamical and statistical simulations indicate that the track line for the PNE cruise will be too far south for getting drifters near the SPURS mooring site.

Given the cruise schedule (which appears to be ever-tightening ... I've learned from Claudia that another day at sea has been removed from the schedule for the cruise) and the fact that the proposed deployments will be before all but one (20N 38W) PNE mooring, Claudia won't have flexibility to divert further north for more optimal deployments.  My understanding based on the discussion so far is that we will be proceeding with regular SVP drifters for PNE, leaving the salinity drifters for more targeted cruises.

    Best,
    Rick

Ron Brown drifter release strategy

Rick et al.,

I made two drifter simulations, using the "Multiple Drop Mode".

The first simulation release a line of drifters on your leg from 20.5N/38W to 20.5N/32.6W.

The second simulation release a line of drifters assuming you can sail north to 23N at 32.6W.

As you can see, the simulations suggest that you should make most of the drifter release when you sail north toward the east of the WHOI buoy, located at 25N/38W.

Maybe we can try other cruise paths.  What do you think?

Drifter Trajectory Simulation tool available

Using the "Multiple Drop Mode", I release a total of 20 virtual drifters, in a 2 by 10 configuration.  To obtain the following 20 drifter trajectories only takes 20 second!

Drifter Trajectory Simulation tool available

From the SPURS web site, under "SPURS Data" and "Drifters" (soon to be replaced by "Drifter Trajectory Simulation"), I released 12 "virtual" drifters, using the "Single Drop Mode".  The velocity hourly data from the ROMS model during August-September 2011 are used to calculate the drifter trajectory.  Currently, there is a limit that each user can release no more than 12 drifters at a time, mostly for computational considerations.  To get the trajectory below takes about 45 seconds.

Simulations

From Rick Lumpkin,

The Ron Brown is unfortunately not going to be able to divert as far as 23N 32W from the PNE trackline, which runs from Bermuda to 20N 38W to 20.5N 23W, then to Eq-23W and finishes in Barbados.  Ship time will be tight, and although there is usually a spare day built into the schedule, all but one of the moorings would still be in the future as the ship is passing south of the SPURS area.  In other words, the chief scientist (Claudia) won't yet know if that spare day is needed for mooring operations, should a problem develop there.

I've run a Nikolai-style simulation using the observed probability distribution functions of all drifters in the area, and released simulated drifters at 20.5N 23W and at 20.3N 28W.  The attached figures show the results, with shading indicating log10(probability) and a star at the SPURS mooring site.  In both cases the drifters are likely to pass south of the mooring at 25N 38W.

Deployment Proposal

Here is a more comprehensive deployment plan proposal:

Let's leave it up for a few days for comments by the group and then we can go ahead with the simulation.

1)deploy 10 SVPS and 10 SVP from the Strasse cruise inside the ~150KmX150Km Strasse box centered at 25N, 36.5W. We hope these drifters will advect westward and enter the small SPURS box in time for the Knorr cruise;
2)deploy 5 SVPS and say 15 SVPs from the Pirata cruise (Lumpkin and Schmid) in September say 23N, 32W tentatively. Again, they should drift N Westward and will enter the SPURS domain;
3)deploy 9 SVPS from VOSs Colibri and Toucan between November and February at ~25N,38W; say one deployment in November (3) one in January(3) and one in February (3)
4)deploy 15 SVPS will by Ray (Knorr cruise) inside the small SPURS box in October say 5 triplets evenly distributed along the north-south eastern side of the box;
5)deploy 7 SVPS east of the Small SPURS domain (25N and 35.5W) at the end of the Knorr cruise;

Best,

Luca and Gilles

wonderful plan, and add in 1 additional 5 SVP and 5 SVPS (from French/Spain funding), that will be deployed in a batch, roughly 15-20 days after the 10 SVPS + 10 SVP array. We are not sure on where those batch deployments will be done, but probably still in the 150 kmx150 km box centered at 25N/36.5W.

Cheers, Gilles.