28 January 2001 - JR58 and the Yellow Submarine
RRS James Clark Ross Diary
Noon Position : 62° 55' South, 50° 20' West.
Distance travelled since Grimsby: 18,350 nautical miles
Air temperature @ noon: -0.2 degrees Celsius
Sea temperature @ noon: -0.1 degrees Celsius
Conditions - Foggy, horrible and can only see 200 m.
And so the second half of the season starts, the half which consists mainly of science - the only exception being later on, when we pop into South Georgia. This will be for the opening ceremony of our new station there. We left Stanley on a lovely calm day and headed south across Drake Passage in equally calm weather, to the ice edge in the western side of the Weddell Sea. It is here we will be for the next couple of weeks darting in and out of the pack ice. As we are not quite far enough south for 24 hour daylight, we spend three hours a day in the dark, which is when we get to use our headlights!
These tools are essential in this part of the world as they are used to pick out any growlers in our path which do not show up on the radar. The centre spotlight is fixed and the two outer lights are stearable from inside the bridge which is very useful on turning, or checking nothing is coming our way while we are sitting on a station (nothing to do with trains though).
Growler - A small but extremely hard piece of ice which just breaks the sea surface and therefore very hard to detect by radar, (Stealth ice if you wish). Something you really don't want to bump into on a dark night......or at all!!
As you saw last week, our "toys" on board this time consist of a CTD (of which we are sure our regular readers are familiar), a Multinet for krill fishing, and most importantly a yellow submarine ! More on these later, or probably next week. A description of a CTD and the Oceanography surrounding it can be found on 30 January 2000 diary entry.
Here we have the Autosub (Otherwise referred to as the Yellow Submarine - apologies to the Beatles) away on its first mission amid the heavy snow we were experiencing. All very festive for those of us who did not manage a WhiteChristmas at home this year.
The Return of the Science Section!
By Andy Brierley, Principal Scientist for the cruise
On this cruise we are sending the autonomous unmanned vehicle (AUV) Autosub-2 on missions beneath sea ice to make measurements of Antarctic krill distribution and abundance, and of ice thickness.
Autosub-2 has been designed and built in Britain by engineers at the Southampton Oceanography Centre and, over the past two years or so, has been made available to scientists to make observations that conventional research ships could not make. Autosub-2 is torpedo shaped, about 7 m long and weighs about 2 tonnes. It is basically an unmanned yellow submarine that can carry a variety of scientific instruments, driving them at 3 knots to inaccessible parts of the ocean.
James Perrett working on some of the electronics for AutoSub.
We have equipped Autosub with a scientific echosounder that can both
detect krill and measure ice thickness. The deployments in Antarctica are part
of a collaborative research project called USPIS (Under Sea Ice and Pelagic
Surveys) between BAS, FRS Marine Laboratory Aberdeen and the Open University.
Who said it was mid summer down here? Krill are at the centre of the food web in the Southern Ocean and their lifecycle is believed to be linked closely with sea ice distribution. However, the under-ice environment is difficult to study, and there are few direct observations of krill beneath it. Most theories about krill and ice so far are based on circumstantial evidence. Although some ships can break through ice, when they do they disrupt the habitat; SCUBA divers can penetrate short distances through ice holes and observe krill, but cannot tell much about what is going on under ice over long distances. In order to understand more about how much krill there is around Antarctica, and why the krill are where they are, we need observations of krill under ice.
Sea ice around Antarctica extends and retreats each year from a maximum area of 20 million square km in September to 4 million square km in February. This annual extension and retreat of ice has major implications for the Earth's climate and ocean currents, and we need to know more about ice thickness to predict, for example, how the oceans might respond to global warming. In the Arctic there are lots of measurements of ice thickness. Many of these were made from nuclear powered submarines during the Cold War period, but since Antarctica did not have such strategic importance, there are few ice observations by submarines there. Autosub now gives us a brand new way to make observations of ice thickness as well as the krill beneath it. We will send Autosub on missions that take it 20 km into the pack ice and back again. The missions will last about 12 hours and for most of that time the vehicle will be on its own. We will make measurements from RRS James Clark Ross in open water that complement those that Autosub is making under ice, and meet up at a pre-arranged position to recover the vehicle and download the data it has collected.
Hero of the Week
The Autosub web site Under Sea Ice Pelagic Studies - The Autosub programme on board the JCR