ALR-1 (aka Boaty McBoatface) makes its second Southern Ocean mission!
|Boaty slowly making its way into the abyss. A curious sea bird examined Boaty as it cruised on its way from the ship. We have found sea birds to be forever curious of any large object, including whales, ships, and auto-subs!|
What is an Autosub Long Range (ALR)?
|Guiding the auto-sub Boaty into the waters of the Orkney Passage region of the Southern Ocean. That is Andy and Povl with arms outstretched, and Rob with the red line.|
Challenge #1 - Intense pressures in the ocean abyss
Challenge #2 - Navigation
Boaty does an improved version of dead reckoning by using an onboard velocity meter called an ADCP (Acoustic Doppler Current Profiler) essentially the same as the one installed on the ship's rosette and discussed in an earlier post to this blog. When it is operated in “bottom track mode”, Boaty can accurately measure its speed and direction relative to the bottom. In this way, Boaty can integrate the speed against time to determine its location. There is some error in the calculation (measurement uncertainty, heading misalignment, and otherwise), which are expected to result in a 1% position error relative to distance traveled.
Challenge #3 - Steeply sloping bathymetry
|Kurt Polzin next to Boaty, examining test readout from the microstructure device that measures ocean turbulence. Checks and double checks are essential to ensure reliable data is returned from Boaty's mission.|
Challenge #4 - Collecting oceanographic data
The first mission also had an issue with the ADCPs. Hence, these were reprogrammed for the second mission, with a resulting retrieval of 100 m ranges of velocities around the instrument. We were able to use this velocity data to map out the bottom currents and bottom temperatures along the western flank of the Orkney Passage. We have used that information to inform more targeted surveys with the CTD and VMP profilers.
Challenge #5 - Interpreting the oceanographic data
Preliminary assessment after two missions to the Orkney Passage
|A curious sky one afternoon while deploying Boaty in the Southern Ocean. This was the day when a number of whales were feeding near the ship. Note the sun rays lighting up the distant sea on the horizon.|