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Feb 4 - Science Action

Date: Sunday 4th February 2007

Position @ 1200 Local (GMT): 75°42.8 South, 026°21.8 West. Off the Brunt Ice Shelf
Next destination: Halley Station on the Brunt Ice Shelf, Antarctica..
ETA: 15th February 2007.
Distance to go: xxx. nmiles. Going off for Science Cruises first before heading back to Halley.
Distance Since Montevideo. : 14415.0 nmiles. Plus lots for our Ice Navigation this Season and more for Moorings and Buoys.
Current weather: Overcast, Fine and Clear.
Sea State: Surrounded by Pack Ice.
Wind : South'Sou'Westerly, 12 Knots.
Barometric pressure: 991.7 Hpa
Air temperature: -6.6°C
Sea temperature: -1.7°C

Click to Enlarge.
Click to Enlarge.

Up to date position information is available courtesy of ‘sailwx/info’ taken from our Metrological Observations..


The RRS Ernest Shackleton is a Science Platform this week.  Last weekend we were off the South Orkneys and started our program of Science, which has continued throughout the week with only a very brief call at Halley to pick up additional Scientist, Andy Warner.  

But what are we doing in our program of science, you may well ask ?

For the answer to that, I refer you to our Principle Scientist, Keith.

You can identify Keith at the 'Principle Scientist' because he is the one who gets to live in Cabin 513, the 'Ch.Scientist's Cabin.  This is remarkable in that it is the only FID Cabin with an en suite bedroom, a DVD, Hi-Fi and Television, and even a fridge for a cold beverage... not that 'cold' is a particularly necessary item down here in Antarctica !!


THE WEEK ON THE SHACKLETON 

Click on all Images to Enlarge.

 

Between South Georgia and the final call to Halley the ship has a science project to undertake. This represents a bit of a departure for RRS Ernest Shackleton, which is principally a logistics ship, supplying bases with food, fuel and personnel, and removing personnel and waste material. The science project is part of the BAS core science physical oceanography programme, and has meant configuring the ship as an oceanographic research platform. In essence, a winch had to be installed that was capable of lowering an instrument package to the sea floor (and then bringing it back to the surface again!) so that the properties of the ocean could be measured. We also had a half-container converted to a lab (affectionately known as the CTD shack), and positioned near the winch.

Outside and In


The instrument that is lowered is called a CTD package (conductivity-temperature-depth) and measures the salinity (saltiness) and temperature of the water, and also the amount of oxygen that is dissolved in it. These properties, which change as you go deeper, act as seawater’s signature, allowing us to work out where it has come from, and what has been happening to it on its travels. For example, we can see whether it has been diluted by fresh water melted from the base of ice shelves. The CTD also has a rosette of twelve water-sampling bottles, which allows us to take water samples from anywhere throughout the depth of the ocean. The water samples can be used to check the calibration of the CTD sensors, and also allow us to measure more exotic tracers in the ocean.

  Deploying the CTD in the Sunlight.


Apart from the CTD work, we also wanted to deploy and recover instrument moorings. The CTD gives a very high accuracy snapshot of the ocean properties, but the instrument moorings, which remain in place for up to two years, give long time series of data from fixed depths. Long records are important, as they can show us how the properties change with the tides, seasons, and even over the years. The moored instruments measure speed and direction of water flow, and salinity and temperature. Moorings consist of a big weight at the seafloor (we use old train wheels, which Steve B thinks is a waste of perfectly good rolling stock hardware) connected to a line kept taut and vertical by sub-surface floats that provide buoyancy along its length. The instruments are simply attached to the line. The top of the mooring is always well below the surface, partly because we are mainly interested in what’s going on in the deepest few hundred metres of the water column, and partly because, if they were near the surface, passing icebergs would wreck them.

 

  Webeditor's Interpretation of a 'mooring'. ( not entirely to scale... or accurate ?).

 

  Releasing the Moorings in the Twilight

 


The science team is seriously multinational. Of the five of us on board (we’re picking up a sixth from Halley), we have five different nationalities: Keith (English), Povl (Danish), Lars (German), Martin (Swedish) and Phil (American). Added to the mix is the unstinting assistance of the dentist Burjor (from New Zealand), and Vicky, the ex-Halley doctor, who, I admit, is also English. The mix seems to be working well.

 

_ - - -


The work is broadly split between the northern Weddell Sea, and the southwestern Weddell, northwest of Halley. We have done much of the first half, though some jobs remain to be completed during a couple of days we have available when we sail north to return to the Falklands. The majority of the work is in the south, and constitutes part of a study into the waters that flow up onto the southwestern Weddell Sea continental shelf. It’s when they are on the continental shelf that the waters get cooled and converted into a dense, cold, oxygen-rich water mass that flows off the shelf, and down to the deep Weddell Sea. Eventually they leave the region via the moorings that we’ll be deploying in the northern work area. The deep waters leaving the region are an important contribution to the global oceanic circulation, and can be traced as far as 40 degrees North in the Atlantic Ocean

  The Proposed Deployment of Moorings this year (Red Crosses).


So, tomorrow (Saturday 3rd) we pick up Andy Warner from Halley, the sixth member of the science team, and then head northwest towards the sites of the first of our moorings. As always, we are at the mercy of the sea ice: what it allows us to achieve remains to be seen.

Author : Keith Nicholls, Principle Scientist.


Wavey Davey’s Weekly Wit Spot.

Wavey has just about recovered from his very expensive last period of leave ashore.  When asked 'why was it such an expensive leave ?', he told me that he had to replace every last window in his house.  

It wasn't until he had finished the whole installation that he noticed he actually had a crack in his spectacles ?!


THE NOT-SO-EXCITING ADVENTURES OF POSTMAN PAT ...

Postman Pat Part Seven : -

We left Postman Pat about to embark on cruise from the Mersey: to where, no one knows. 

To the sandy shores of South Georgia, perhaps… 

 On the beach at Y K K E P. 

Or to the tropical jungle and waterfalls of South Georgia perhaps…
Where he met his mate Bob, who took him up to visit the grave of Sir Ernest Shackleton…    

But South Georgia being South Georgia the snow soon came down…


His PP trapped up to his knees in snow or worse…

See next week’s very exciting episode of the not so adventurous adventures of Postman Pat. 


WE REALLY ARE BLESSED 

It is sometimes hard to step back and 'smell the humus' !  We all get so busy with our duties onboard the Shackleton, that we occasionally forget to stop and pause to look out of the window (or porthole).  But when we do, we are blessed with what must be one of the greatest sights on Earth. It occasionally takes someone like Dentist Burjor to come alone with 'fresh eyes' to remind us just what it is that keeps drawing us back down to Antarctica year after year.  I am sure I have waxed lyrical about the beauties of Antarctica in these pages before, but this week has been particularly nice.  We are down in the Weddell which always seems to be deplete of weather !  Looking at our weather charts each morning, it seems that violent weather systems are going on all around us and meanwhile we are caught in an envelope of calm !   The calm is depicted by the Isobars being well-spaced apart and not crunched up close as it is up near South America.

  Click on Image to Enlarge Today's Chart.

Despite the calm weather, we have still had overcast and cloudy, but then we have also had sunny and bright days which are definitely the nicer option ... unless, of course, you are our WEBCAM !  

We had a webcam fitted to the Shackleton last Summer and it has been transmitting images back to Cambridge every hour since.  You can see the view out of the bridge windows anytime at the following link : http://www.antarctica.ac.uk/Living_and_Working/Transport/Ships/Webcam/shackleton.php

But it is only since we have come down to Antarctica that we seem to have been having real problems with the Webcam.  And why ?? Because it has been TOO NICE.  I am certain this little camera is fit for purpose when mounted on top of a computer at home and pointed inwards to the Internet Chat Room Chappie who is projecting images of his/her face to his/her friends.  But I am not too sure it was designed for being bombarded by high intensity UV rays 24 hours a day and 7 days a week.  Poor camera.

  The light levels the poor camera is looking at all day, every day !

There may be avid viewers (hello Vreni) who may have noticed how we are having to try our hardest to cut down on the amount of light getting to the lens recently.  With all this sunshine bouncing off the pack ice that lays all around, it is not enough to just draw the UV Protection sunblinds that cover the bridge windows throughout it's 360 degree views.  And to augment these, I owe a big thank you to our own Ralph who came to the rescue with a pair of broken sunglasses ! 

Click to Enlarge the Aperture

Using the most advance technological know-how, yours' truly stuck the one remaining lens from the broken sunglasses into place with a highly technical bit of tape and luckily, the reduction is enough to allow the camera to work for the best part of the day.  I shall be asking our IT department back home in Cambridge to look into this problem and at the very least, .... replace our broken pair of Sunglasses !!!

We trust you will bear with the webcamera when it occasionally goes to light or too dark, but the auto aperture cannot cope with the extremes of illumination we seem to be suffering down here in the Weddell Sea.


FINALLY for this week - and I haven't room for the other items I wanted to air this week - we are continuing with the Science in an  ever-increasing density of Pack Ice which is keeping the Deck Officers fully amused with the crunching and crashing into floes, brash, and pancake ice.  It is great fun for the 'drivers' but of late, I have realised that the scraping of Ice down the side of the vessel can resonate you out of your sleep and almost out of your bed !!  It is just one more aspect of Antarctica that you cannot fully appreciate from the pictures.  Until they invent a camera that can record the sights, the sounds and the smells altogether, you just have to take our word for it and experience this fantastic place 'second hand'.  But then again, you will be sleeping peacefully in your beds tonight whilst we on the Shackleton will be contending with more cracking, crunching and shuddering ! 


Forthcoming Events: Continue with Keith's program of CTD's and Moorings in the Weddell Sea..  

Contributions This Week :  Thanks to Keith Nicholls for his excellent piece and Ralph for the broken sunglasses.

Diary No.11  will be prepared on Sunday 11th February 2007 for publication on Monday 12th February.


Stevie B

Radio Officer.