Drifter Deployment Plan for 2012

Drifter deployment plan for 2012

by Luca and Gilles

1)     STRASSE CRUISE. Chief Scientist: Gilles Reverdin. Dates: August 13 (Las Palmas) - September 12 (Ponta Delgada).

We will deploy 15 SVPS (10 from SIO-NOAA, 5 from France and Spain) and 16 SVP (10 from SIO-NOAA and 6 from France) (all drogued at 15 m depth) inside the ~150KmX150Km Strasse box centered at 25N, 36.5W. The drifters should move westward and enter the small SPURS box in time for the Knorr cruise;

2)     Knorr CRUISE. Chief Scientist: Ray Schmitt. Dates: September 6 (WHOI) - October 9 (Ponta Delgada).

We will deploy 18 SVPS (from SIO-NOAA) in 6 triplets evenly distributed along the north-south eastern side of the SPURS box, centered at 25N, 38W;

3)   RAPID CRUISE. Chief Scientist: Gerard McCarthy. Dates: October 8 (Southampton, UK)-November 9 (Bahamas). We will deploy 9 SVPS (SIO-NOAA) at the nominal location of 25N, 35.5W between October 22^nd and October 24^th

4)  VOS deployments of salinity drifters: deploy 9 SVPS (from SIO-NOAA) from Colibri and Toucan between November and February at 25N,36-39W; say one deployment in November (3) one in January(3) and one in February (3). Two additional SVPBS French drifters could be deployed is available

5) VOS deployment of SVP drifters: starting in December 2012, we are planning to deploy 8 SVP drifters (SIO-NOOA) per month for the duration of one year in the large-scale SPURS domain.

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.