Wednesday, March 27, 2013

Floating Tupperware

“Why did someone tie a garbage bag to a piece of Tupperware and an oversized Styrofoam doughnut?” some cruise ship passenger might ask if they pass by the SPURS area. 
Acceleration sensor from below (Photo: Anonymous)
There is no doubt that a lot of the instruments we deploy look quite strange. But in oceanography it is all about the inner values, the sensors that provide us with information to understand how the ocean works. In this case the garbage bag is a drogue, which ensures that the float attached to it follows the surface currents of the ocean. The Tupperware is a waterproof GPS antenna for exact position data and the doughnut is an acceleration sensor, which can be used to infer energy input into the ocean by the wind and waves. 
Simon Morisset prepares his surface drifters
The system was developed at LOCEAN in Paris and Simon Morisset takes care of the deployment on board.
There are lots of different autonomous platforms involved in the SPURS program. Surface Drifters of various kinds, profiling floats and gliders provide a great coverage of the area both in time and space independent of the ship.
Kintxo Salvador and Miquel Rosell prepare the drifter
On the SARMIENTO we deployed three additional types of autonomous instruments additionally to Simons surface drifters. One APEX float which profiles the water column and a different kind of surface drifter that measures gradients in the upper meter of the water, using three tightly spaced sensors that record salinity, temperature and pressure every second. Then there is also the ASIP (AirSeaInteractionProfiler), which measures turbulence in the upper ocean up to the surface.  More on this instrument later…

All these instruments need to be recovered after deployment. Which should usually not be to hard, since all the instruments send out precise positions via satellite. But the ocean is not a controlled lab environment and sometimes things can go wrong…
Then the odd looks can actually come in quite handy in order to locate a tiny instrument on the open ocean between waves and sun glint.

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