28 February, 2006 Halley
Well, everyone’s about to leave us in peace. Almost everyone went early on Saturday morning, but five or six spare summerers remain until the second and final exodus on Monday morning. If all keeps going to plan, I’ll drive to the ship with them, wave them off, then drive back to the base without them.
A few days ago I managed to get off the base for a few hours for the first time (bar the quick trip in the hairy-plane). Me and a couple of meteorological types headed off to a radio microbarograph site to dig it out of the snow and raise it by a meter or so, ready to work for another year. This involved a lot of futile digging, as we weren’t sure where the box with the instrument in was, but eventually we managed to find it and haul it to the surface. It was fantastic to have a little ride out on a skidoo over virgin snow on a beautiful day. The sun was shining through holes in advancing clouds, picking out spots on the plateau behind a darkened base, and all was unusually quiet. Until the music we took with us was turned on, of course.
The twin otter that’s lived here over the summer left a couple of days ago, with many people down at the airstrip to wave the pilot and mechanic on their way. After taking off they turned, gave us a quick fly by, then headed off to Rothera and eventually the UK where they’ll get serviced ready for next year.
I’ve declared my leg healed, so feel much better now that I can go out and kite in the setting sun. Last night was magical, with a scattering of low clouds, a thin crescent moon and a planet sparkling just above the horizon.
This year we’re trying to collect data from an ‘Ozone Depletion Event’ (ODE). This is when the formation of sea-ice destroys low-level ozone. We hope to fly a small blimp through the ozone-depleted air and measure how thick this layer is. We will attach a normal sonde and an ozone sonde to the blimp line. A sonde is a small, light piece of equipment that measures wind speed, direction, pressure, temperature and humidity. The ozone sonde will measure the amount of ozone. We will fly the blimp during our springtime- September/October, when the sea ice is breaking up and reforming again. But first we have to practice using the equipment.
To save helium and preparation time we will keep the blimp inflated between flights. To keep it from flying away (it gets very windy here) we have a weather haven to store it, and the helium that will inflate it. We’ve borrowed this particular weather haven from a site in Berkner where some other BAS scientist were drilling a very long ice-core for studies on past-climate. Fortunately our intrepid Field Guide, Simon spent a season there and instructed us in putting it up.
Two banks of 16 helium cylinders each are kept inside this box-on-a-sledge. The box also has light and heat. We will be doing these blimp flights at very cold temperatures so the area surrounding the helium banks needs to be warmed up before they’re used. This box will also go in the weather haven but for today’s exercise we kept the box outside of the tent.
The bottom frame. We’ve labelled all the bits up with different coloured electrical tape to help us do it in the cold and dark. The whole tent is 14x28foot.
Constructing the frame. The whole operation took 2 hours.
One end of the weather haven has a large door that the blimp should easily fit through. The other end has a small door.
Next… a test flight.
There was an aircraft due in today and because of safety reasons, regulations say that we aren’t allowed to fly the blimp on one hour either side of the aircraft’s ETA. This meant that we wouldn’t do a proper flight all the way up to the boundary layer (400m or so), but we did do a good test of the entire system. It was a little slow to begin with, we had trouble with the regulator from the Helium banks to the tube, and then some of the tubing was blown off- but we got it all sorted. Inside the sonde set-up was a little slow as well, but this will just take practice. Eventually we were at the point where the blimp was full and the sondes were transmitting data… we were ready to fly.
The blimp had to squeeze out of the weather haven but there were many curious hands to help, so there weren’t any problems with that. We put the blimp on its resting rope before contacting comms to notify them of our flight (however brief). Then we set the automatic winch off, had someone at hand on the manual winch and put it up 10m or so. Then we attached the sondes, which were happily whirring away. The flight went well. Very well, there were hardly any hiccups and it was all good practice for the real data flights this spring.
In the spring when we’re (hopefully) measuring an Ozone Depletion Event we will be doing all of this in the bitter cold for hours on end. We will be measuring wind speed, wind direction, pressure, temperature, humidity and ozone concentration.
At the beginning of the month most of the base was involved in a major incident scenario, designed to test our response to a serious accident involving multiple casualties. Down here you can’t just call 999 if things go wrong so everyone must be trained and know what to do. John and Vicky have been very busy over the last few weeks improving the procedures and planning the details of the event. The scenario took the form of a plane crash at the skiway, leading to serious injuries to the pilot and three passengers.
The next day the AIS transmitter masts were raised. These are the tallest erections in Antarctica and are 46.3m above the snow surface after they were raised this year. There are two masts that hold a Log-Periodic antenna curtain between them. Because they are so high, raising them took two days. The mast erectors Fish and Jacko took it in turns to climb the masts and Bryn and I, were the other climbers. Bryn is the outgoing AIS engineer and I am taking over from him. On the first day Fish and Bryn climbed the west mast.
In order to raise the masts you have to fit a new 10 foot section of mast to the top. So you drop the antenna curtain onto the ground. Get a pulley onto the top of the mast. You then haul a gin pole (long pole that fits to the top of the mast) with another pulley on it and fit that to the top of the mast, you can then pull things higher than the current top of the mast. You then haul the new section up and fit it to the top. The next day it was mine and Jacko’s turn to climb. It was a beautiful day and we raised the mast by lunch time.
Once you have raised both masts you can then raise the antenna curtain again. The antenna had to be checked as it is raised and there was a bit of damage between insulators and the dipole wires. However we fixed everything and it all worked well later. While we were doing all this work other people were invited to climb the masts as it is not often that you get an opportunity to climb them (they are transmitting a lot of the time with 10kW pulses 250 times a minute at wavelengths about the same size as a large human). Only one person apart from Bryn, Fish, Jacko and Me got to climb and that was Kirsty. She was just lucky and was there when we weren’t too busy. So she is only spectator to have been up the largest constructions in Antarctic this summer.
We left the base early on Saturday morning for the long drive to N9. The vehicle mechanics had already been up for hours getting the vehicles warmed up, and setting off in the slower vehicles – a bulldozer and crane which were being sent back to Cambridge for a full service. We left Halley just after 8:30am in a convoy of seven sno-cats, each one towing a sledge full of cargo or waste.
The drive to N9 took us about five hours so we arrived just in time for lunch. Since the ship has come from the north they had a plentiful supply of fresh fruit and vegetables and I was able to enjoy a salad for the first time in a year.
It’s getting rather late in the year for a ship to be this far south, as the temperatures begin to drop rapidly now the sun is starting to set. During the journey to reach us the ship sailed through some rough seas and in these temperatures the spray freezes on impact, causing up to 4 inches of ice accretion onto the hull in places.
The temperature dropped to -20C last night, and we were able to stand on deck and watch the sea freezing in front of our eyes. First the surface becomes waxy then ice crystals form and start sticking together. These patches grow in size and the constant motion of the tides pushes them against each other to form flat, circular lumps known as pancake ice.
Another sign that the sea is freezing is the sight of sea smoke. This was the first time I had seen it close up and it is amazing – the whole surface of the water appears to be evaporating and any wind creates swirling vortexes much like the way it plays with spindrift at Halley.
With all these signs of the approaching winter, the captain is no doubt keen to get underway and return to warmer waters. The second wave of sno-cats (carrying the remaining passengers and cargo) is due tomorrow, then on Tuesday we will sail along the coast to a nearer Creek to say one last goodbye to the new wintering team before heading northward.
It was a strange and yet exhilarating feeling driving back last night from the ship. We are going into winter now, only 16 of us for the next 10months! Right on cue as we left the weather started to get worse, when we did eventually arrive back on station the visibility was low, there was blowing snow and it was pretty cold. I’m sure someone must have flicked some magical weather switch as we drove away from the ship���welcome to the Antarctic winter folks!
The 2006 Winter Team:
Nicola Robinson, Andy Warner, Dave Anthony, Mark Wales, John Withers, Vicki Mottram, Chris Oakley, Bob Pratt, Simon Herniman, Alex Gough, Anto Brennan, Fran Williams, Brian Hunter, Liz Kempster, Kirsty Stead, Jules Rix