Glider School

After returning from the SAUC-E competition, the Oceanic Platform of the Canary Islands offered some of us the opportunity of attending a two-week course on Gliders.  By that time, only two of us had not already made plans. In my particular case, I had a lot of work with my master thesis and was not planning in going anywhere.

The course was divided in two main areas, one concerning the technological aspects of the vehicles and the other one about its scientific applications. For the first part of the course, we were introduced to the physics related to the glider’s movement, which basically describe the modification of density needed to alter the buoyancy, depending on several parameters such as temperature and salinity, both of which have an impact on the average density of seawater. We also dedicated some time learning about the electronic components used in gliders for computation, communication and navigation and were introduced to the software for remote operation.

During this first part we also learnt about the main aspects of glider operation, such as how the different paths and parameters are set to define the glider flight, how to properly ballast the vehicle, and we even got the chance to deploy (and recover) a glider. The deployment  of the glider was quite interesting, we went on a boat to open sea and gently dropped the glider in the water. When the glider was ready, the operator commanded the vehicle to submerge at a certain depth and it certainly tried, but the vehicle was able to detect that the desired depth was unreachable because of the sea floor being higher, and came up again. The vehicle is quite slow in its operation and watching it dive and come up again can be quite boring, but then again speed is not required for the applications of these vehicles. The recovery was definitely not easy, I did not directly participate but watched the entire scene as it happened.

The course also included opening and examining the interior of several gliders such as the Slocum, the Spray and the SeaGlider. The first two gliders are quite easy to open and the operator has full freedom to do it, but in the case of the SeaGlider, opening it voids the warranty. The Slocum Glider has a very polished design and it seems very comfortable to work with. In contrast, the Spray Glider looks handmade and there were a lot of things that remembered us to the design of the Avora AUV. Finally, for the first part of the course we also had some presentations from Bluefin Robotics on the Spray Glider, from Liquid Robotics on the Wave Glider and from ACSA-Alcen on the SeaExplorer. The Wave Glider is a very interesting vehicle, although some people do not consider it a glider, and the SeaExplorer is the first European glider.

The second part of the course was dedicated to the scientific applications of the gliders. We learned about different types of sensors used to analyze the properties of the seawater, such as salinity, temperature, pressure, turbidity, dissolved oxigen, etc. Also, we had quite a lot of presentations from several groups and universities explaining the different sensors, the applications of the gliders, results they had obtained, and more. This part of the course was certainly interesting, but for a technical person such as myself, a little bit difficult to follow.

I was very impressed by the presentation given by Dr. Oscar Schofield from Rutgers University on how the ice cap melting affected quite a number of parameters of the global seawater and how this produced a chain reaction which ended with several polar species being unable to feed. Another thing I enjoyed about the course was the presentation on the Wave Glider, it is an incredible technology and a demonstration of how to intelligently harvest energy from the environment for long term operation.

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