This is a re-post from the Polar Gliders team blog published on 3 July 2020
Four new Autonomous Underwater Vehicles called SeaExplorers have arrived in Gothenburg. They are buoyancy propelled gliders developed by the France based Alseamar-Alcen that yo up and down in the ocean collecting physical and biological measurements. These gliders were brought to Gothenburg by Ola Oskarsson through an initiative called Voice of the Ocean (VOTO; http://voiceoftheocean.org/) and will be used for an oceanographic long-term project to measure oxygenation and the physical ocean dynamics of the Baltic Sea and Skagerak-Kattegatt.
Two Polar Gliders members, Seb Swart and Louise Biddle, along with Bastien Queste, a Lecturer in Marine Science at GU, are working closely with VOTO to help set up their glider infrastructure and sampling strategies. The project aims to kick off after the 2020 Swedish summer, but before that can happen, an intense week of SeaExplorer training was had. Estel Font and Marcel du Plessis from the Polar Gliders group joined Seb and Louise at Nya Varvet for the training week.
The training was run by Nicolas Buisson from Alseamar. Monday was an intense day of theory, while Tuesday we managed to get outside and prep the gliders for their first deployment. Wednesday was the big day when two of the four gliders were deployed in the Kattegat. There was a good mix of nerves and excitement around, and to make things even more interesting, the gliders had to dive across 14 sigma units of density, almost double the units of the SeaExplorer’s “extreme case” scenario!
After a slight readjustment of the deployment location due to some trawler boats hanging around, the gliders were put in the water at lunchtime, which made for some interesting remote cafeteria piloting. As Nicolas was on the boat, this left Louise, Seb and Marcel, who stayed behind with two others from MMT, as land pilots to navigate the piloting software (albeit with a remote Alseamar pilot looking over our shoulders). Wednesday piloting was a success and we managed to eventually get the gliders to dive across the strong freshwater stratification!
Thursday morning was recovery day. Marcel and Seb joined the boat team to go pick up the gliders and beautiful conditions meant that spotting them was easy. Upon collecting the first glider (SEA056), we noticed streaks of black paint and two big dents! A big warning that navigating these waters is going to be a challenge for the VOTO pilots! Nonetheless, we had both gliders on board in no time and with the lovely Swedish sunshine, we stopped off for a lunchtime swim in calm 19°C water.
On Friday we consolidated the deployment, went through some case studies for future missions, performed compass calibrations and began work on the other two gliders. The SeaExplorers undoubtedly passed the test (with a few hiccups) and look like they will be a great instrument to monitor the Swedish waters. Overall, it was a fantastic week of training and a huge thanks to VOTO (Ola Oskarsson and Olle Petersson) for the opportunity to learn about a new instrument and to Alseamar for the training course!
Written by: Marcel du Plessis, Seb Swart & Louise Biddle.
