04 February 2001 - Snow, Rain and More on Autosub
RRS James Clark Ross Diary
Noon Position : 62° 49.9' South, 47° 02.1' West.
Distance travelled since Grimsby: 19,091.1 nautical miles
Air temperature @ noon: 0.5 degrees Celsius
Sea temperature @ noon: 1.2 degrees Celsius
Conditions - Foggy, horrible and can only see 200 m.
Snow, Penguin Traps and Rabbits
We continue popping in and out, in and out, in and out of the ice continually throwing the yellow sub over the side, only to find it returning to mother after its mission, like a good dog. It's either relief or surprise each time it comes back, not too sure which though !
There has been so much snow and freezing fog it's really been quite horrible. But it's the Antarctic we hear you cry ! Well yes that is correct, only that it is the summer, and it can be usually quite gorgeous down here. The latest theory is that we are just not far enough south to get out of the northerly airstream bringing down all the warm moist air. So much so, that when we were deep in the pack ice on Monday it was actually raining - all very bizarre. The real point of mentioning all the snow and ice (and the occasional rain) is to pay tribute to all those involved launching and recovering all the gear - which is most of the crew, and also to the Autosub guys who changed its batteries the other night. An eight hour job in the freezing cold.
Are these Penguin Traps ? No it's just science at work ....
By Mark Brandon, The Open University.
Hi, As Andy said last week, one of the things that Autosub 2 is going to measure as it flies beneath the sea ice is the thickness of the ice. Why on earth would you want to know about the thickness of the sea ice??? Everyone knows that heat flows from hot to cold. When you get up to high latitudes the air temperature is generally colder than the ocean. Even now in summer, air temperatures are about 3 deg C and the ocean 1.8 deg C (remember the ocean is salty so the freezing point is lower than 0 deg C). The temperature difference means that heat is flowing from the ocean to the atmosphere.
When you put sea ice on top of the ocean it is a bit like putting on a blanket in bed - it slows the heat loss down. Snow on top of the sea ice is just like putting on another blanket. This means the amount of heat lost depends the thickness of the ice and the thickness of the snow. Autosub 2 can measure the ice thickness by flying under the ice. The only reliable way to measure the snow depth is to actually get off the ship and measure it using some very high tech equipment.
To use hi-tech equipment I need some trusty helpers, so a big thanks to Miles, Mary, Paul, Eric, Mark and Andy. Whilst Autosub is on a mission we steam into the pack ice and pick a "typical" ice floe and go over the side on a basket.
In the Antarctic the snow can get thick enough to actually sink the sea ice. When this happens the seawater that floods over the top of the ice floe mixes with the snow to freeze into "snow ice". In the picture above, Mark and Mary are making snow measurements, and Miles is digging a large pit down to the snow / sea ice. After about 1.4 m, Miles chipped off a couple of samples of ice with a pickaxe. We are going to measure how salty this ice is (once it has melted!). The more observant readers will notice that my trusty helpers seem to be doing all the work on the ice and not leaving anything for me to do; Well someone has to take the photographs don't they?
On one of the first forays into ice caused much excitement, quite rightly, for those who had not seen pack ice before. Not only do you get to marvel at all the different qualities of ice, but the wildlife count is always higher at the edge. So the unofficial quote of the week has to go to Andy Brierley, our Principal Scientist, for pointing out that the animals that everybody could see were in fact rabbits !!
The Yellow Submarine's bit in the middle
The "AUTOSUB" Story - so far...
By Nick Millard SOC
Autosub is an autonomous underwater vehicle developed by engineers based at the Southampton Oceanography Centre and funded by the Natural Environment Research Council. The vehicle has been designed to provide an underway platform with a 'cargo space' easily adaptable to take a wide variety of scientific instruments. It has a networked, distributed control architecture that makes for easy integration and testing of both vehicle systems and scientific payloads. Although designed primarily for measurements in the water column its potential for seafloor surveys has been recognised and science proposals requiring the integration of appropriate survey instruments are currently being reviewed.
Construction on Autosub-1 was started in the summer of 1995 after a five-year study and design period. The first sea trials were undertaken in Southampton Dock in June 1996 and by April 1997, Autosub was ready to undertake a series of more challenging missions of increasing complexity and scientific content. These early missions took Autosub to Florida to perform joint missions with Florida Atlantic University's smaller AUV, Ocean Explorer in the difficult environment of the Gulf Stream and to Bermuda for a demonstration of the vehicle's multidisciplinary data collecting ability. Bermuda also provided the venue for the deepest (500 m) and longest (250 km) mission at that time.
An expedition on board The Fisheries Research Ship Scotia in July 1999 was the first of six campaigns under the NERC Autosub Science Missions thematic programme. The vehicle was fitted with sonar systems to conduct a herring survey in the northern North Sea. It was the same sonar system now being used for the second part of the campaign; a survey of krill under Antarctic ice, operating from RRS James Clark Ross. Other campaigns include; Sandbank studies in the southern North Sea; Measurements of manganese and oxygen concentration in Scottish lochs; Sonar and turbulence studies in the upper ocean, west of Scotland: Novel measurements of the overflow at the sill at the Strait of Sicily, and Subsurface single cell and particle analysis in coastal waters using a novel flow cytometer. Over the two years of the thematic programme Autosub has made 75 missions covering in excess of 2200 km.
The future from 2002 to 2005 lies with work under the floating polar ice shelves to study the physical environment and ecosystems.Technical Details of Autosub
Next weeks page:
Having spent a lot of time on the Autosub we thought that we would dedicate next week to Doug Bone's Multinet and his lovely layers of Krill.
Last, but by no means least, our nomination for crew member of the week
Marc Blaby (Binns) Crane driving in all weathers. Click to enlarge. Note:The photographer waited for nice weather to venture to Marc's post on the foc'sle driving the crane lowering scientists onto the floes to sample the ice. The weather has been less than clement at times...
Answer to question on powering AutoSub: Torch batteries, Yes D-types you get at home, only lots and lots of them !!! In fact up to 5000 of them.
The Autosub web site Under Sea Ice Pelagic Studies - The Autosub programme on board the JCR