The yellow high-tech autonomous underwater vehicle (AUV), also known as ‘Boaty McBoatface’, has successfully returned from an ambitious science expedition deep below half a kilometre of ice.
It is the first time that ‘Boaty McBoatface’ had been deployed underneath an ice shelf, marking a significant milestone in proving the vehicle’s capability and demonstrating the contribution that AUVs are making in helping researchers understand what happens in these inaccessible parts of the ocean.
On this occasion, the AUV carries two sets of conductivity, temperature and depth (CTD) sensors to measure salinity and temperature of the water underneath the Filchner-Ronne ice shelf in Antarctica.
What do researchers aim to find?
Climate researchers are particularly interested in whether more glacial ice is currently being transported into the ocean, as this process is directly linked to rising sea levels. Also, ‘deep water’ forms near the ice shelf, which is a key driver of global ocean circulation and so impacts on the climate systems all over the planet.
‘Boaty McBoatface’ was also equipped with a sensor to detect the turbidity of the water, a micro-structure probe to measure ocean turbulence, and a sensor to measure the amount of phytoplankton in the water. The AUV has spent a total of 51 hours under the ice, travelling 108km and reaching depths of 944m.
Steve McPhail, head of AUV development at the National Oceanographic Centre, said: “Waiting for the AUV to return is – to say the least – exciting, and as a result I was very relieved each time the AUV turned up, on time, and in the right place, circling 900m below the ship. Even then our problems were not over. With the surface of the sea frozen, we needed RV Polarstern’s help to create an ice hole through which we carefully navigated the AUV.
“I am delighted in the success of this mission. For the engineers involved, this was a very challenging deployment that was not without risk. We knew that the environment was harsh, with -20°C air temperatures and sea temperatures very close to the freezing point of seawater. Under the ice shelves there are significant tidal currents and the high southerly latitudes pose difficulties for the AUV’s underwater navigation. Once in the ice shelf cavity we had neither detailed information on the thickness of the ice, nor the depth of the water. We had no communication with the AUV for 90% of its time in the water.”
The AUV was deployed from January to February 2018 from the German research vessel RV Polarstern, as part of the Filchner Ice Shelf System (FISS) Project. The AUV plays a critical role in the project that aims to investigate and describe the current state of the complex atmosphere-ice-ocean system.