Wednesday, 13 June 2018

Summer/Winter?


As people’s thoughts turn to summer holidays my friends keep asking me, “Are you doing fieldwork in Antarctica this summer?” I politely point out that it’s a bit cold in Antarctica at the moment, and dark.

As we head towards midwinter in Antarctica this is a nervous time for someone who has ~30 GPS instruments bolted to remote outcrops, measuring postglacial rebound across a 3,000 km swath of West Antarctica. The instruments rely on solar power between September and April, but as the sun dips below the horizon for a few months the power begins to drain out of the battery bank, and we must nervously wait to see if they make it through the winter.


Ice build-up inside one of the instrument enclosures after the Antarctic winter (credit: Alex Grievson)

We do have an alternative power supply at some sites: wind turbines. But your standard 2-foot wind turbine, which claims to be rated for ‘extreme conditions’ doesn’t always fare so well in an Antarctic storm. When we return the next year it’s not uncommon to find that the turbines have been sheared off their mounts or, if the circuit breaker didn’t kick in properly, the circuit board has been fried.

One turbine has been ripped off its mount and is nowhere to be seen, the other has a blade missing (credit: Alex Grievson)
Trying to service all the GPS sites during the short Antarctic summer is a logistical nightmare. Without knowing the state of the instruments it’s not easy to know what spares to carry. And all these spares have to make their way down to Antarctica in good time*. Once in Antarctica the kit needs to be flown to each GPS site in one of BAS’s four Twin Otters, hopefully in the company of an engineer who has the skills to coax an unresponsive instrument back into life, potentially in rather challenging conditions. It’s one thing mending a circuit board in the comfort of the lab, but quite another when the wind is hitting 50 mph and you have long-since lost any feeling in your fingers.

*at some point last season a cautious customs employee decided one of our cargo boxes was too dangerous to fly, so it got put on a truck somewhere in northern Chile with instructions for the driver to head south…that’s the last we saw of it for several weeks!

Ready for take-off in the Twin Otter. This is everyday work for pilot Vicky and field guide Catrin, but for electrical engineer Gábor having the opportunity to co-pilot a plane is an unexpected perk of the job 

On good days you can work with bare hands (why am I wearing one glove?!) and put your jacket down without fear of it getting blown into oblivion across the ice sheet (credit: Ian Potten)

…or you can sunbathe with a seismometer 

Although it looks sunny, this day was bitterly cold – we had to use a bungee cord to stop the lid slamming shut in the strong wind, and scoffed a massive bar of chocolate to keep morale up (credit: Al Docherty)

Some of you may be wondering how working in such challenging conditions can be described as ‘fun’, but anything that involves ski-ing to work is fun in my book, even if it means pulling a 50 kg sledge along behind you.

Commute to work by plane and ski (credit: Mark Beasley)

It can be a bit of a trek from the plane to the GPS site. Now, can we get these sledges moving…? (credit: Gábor Geréb)

End of a day’s work. The sledges are lighter but it’s an uphill journey back to the plane (credit: Gábor Geréb)
But there are smarter ways to do this. If we are able to monitor how the GPS instruments are doing through the polar winter we can come up with a more targeted servicing plan. Even better, if we can transmit the data from the instruments straight to data hubs around the world we don’t even need to visit them to download the data and clear the memory card. At present, 8 of our GPS instruments are transmitting data, and we can monitor the power status at a further 5; plans are afoot to boost these numbers in the coming season.

Wiring in a modem so that we can track the status of this instrument through the winter. Emergency satellite phone and cereal bar close to hand.

We’ll still get to visit these beautiful, remote spots when things go wrong, but as we equip them all with a satellite modem over the next couple of years we can turn our attention to untangling what the data are telling us.
GPS perched on an outcrop at the edge of the Larsen C ice shelf

No comments:

Post a comment