One of the last activities of the PICCOLO cruise was what we called a 'supersite' – an intensive study of one location over 24 hours, to study how the ocean varies in small time and space scales. We deployed an ocean glider in one place, and a freely-floating trap nearby to collect the particles of biological matter raining out from the plankton in the surface layer. The ship performed lots of CTDs (conductivity, temperature and depth) – collecting water and measuring biogeochemical and physical properties of the seawater. Excitingly, we also deployed an autonomous surface vessel, UEA’s AutoNaut called Caravela. We have been looking forward to deploying Caravela for the whole cruise, so it was marvellous that we got permission from the Maritime and Coastguard Agency to send her on a mission.
The future of ocean science
6 March
Prof Karen Heywood (UEA)
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Caravela is powered by waves – she has fins rather like the tail of a dolphin that move up and down with the waves and propel her forward. All of her scientific sensors are powered by solar panels, and she is very quiet; she really is an environmentally-friendly ocean observing system for the twenty-first century. The Captain of the ship, Will, commented during our supersite that this was the most simultaneous science he’d ever seen – three different autonomous platforms out surveying at the same time as the ship was measuring everything it could in the ocean and the atmosphere. Each platform has its own strengths and weaknesses so they complement each other. This is probably what the future of ocean science looks like.
We think this is the first autonomous surface vessel to be deployed in the Weddell Sea.
Prof Karen Heywood (UEA)
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Piloting Caravela for the 24 hour deployment was quite a task. Although she is equipped with a collision-avoidance system, this only works for ships that are emitting a signal called AIS (automatic identification system). Of course, icebergs don’t have AIS installed so we had to rely on the ship’s ice radar and the expertise of the officers on the bridge to change the heading of Caravela so she didn’t have too many encounters with icebergs or large sea ice floes. We were really grateful to all the officers for their skill and advice which enabled Caravela to safely complete her first Antarctic mission. We think this is the first autonomous surface vessel to be deployed in the Weddell Sea.
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We named our autonomous surface vessel Caravela because it is the Portuguese word for the Portuguese man-of-war, a type of jellyfish that carries a community of organisms beneath it. Caravela was designed to carry an ocean glider, and release it at a selected time. For our Antarctic deployment, we deployed the glider from the ship. We attached a whole host of other sensors to the underside of Caravela for her to carry during her mission. It was a real joint effort with many people onboard contributing a sensor – for pH, dissolved carbon dioxide, chlorophyll and so on. Caravela’s own sensors measure the wind, air temperature and solar radiation, as well as surface temperature, saltiness and currents. Putting all these data sets together is going to be fascinating!