June 4th, 2006

This is a month or so late – I’ve only just found the pictures!

Every week if the weather’s good, Helen (who’s the Marine Assistant) goes out in one of our small inflatable boats (named Discovery by last year’s boatman Andy Wilson, but known to everyone at Rothera as the Flying Mattress as it’s rather saggy!) to do a CTD cast and some water sampling.
CTD stands for conductivity-temperature-depth and is a standard measurement made all over the world by physical oceanographers. The probe measures its own depth by measuring water pressure, and then measures the water temperature and conductivity (which tells you how salty the water is) continuously whilst you winch it up and down through the water.
I got a morning’s trip out on the boat with Helen and Richard to lend a hand, as our boats are fitted with a mechanical winch, and winding 500m of cable out and back takes a lot of effort!

Helen winds the CTD
Helen winds the CTD winch

Whilst we’re out doing the CTD, we also take water samples at different depths, which are then analysed and sent back to researchers in Cambridge and at universities all round the UK. The scientists are looking at variations in trace metal content in the water, and seeing how this changes with water temperature so that it can be used for further studies on climate change.

Curious seal
A curious seal

Going out in a small boat is good fun if you get a nice day (and if it isn’t a nice day, you don’t go!) but you also get see some of the aquatic wildlife in their element – we saw a curious seal nose around the boat and take a good look at us, and other CTD crews have seen whales come close to the boat, which is both exciting and a touch scary!

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