Thursday, August 30, 2007

The Return Of The Sun

Increasing Daylight

The most significant moment of the last few weeks has to be without doubt the return of the sun over the horizon. For while the increasing light and the colourful displays that go with it, preempt its return, the moment that it broaches the horizon for the first time in getting on for four months, is an emotional event.

The Top of the Solar Disc Emerges for the First Time
Watching the sun reappear over the garage catenaries

Like the sun's disappearance, there is great debate around the lunch table as to the actual date, given that a miraging sun may appear a few days earlier and the definition of what the sun being above the horizon really is. The photo above demonstrates beautifully another common sight around base- catenaries. Common, as there is the need for overground cabling in many places to supply power and/or data cables supported on wooden or metal posts that need continuously raising against the incipient accumulation of snow that threatens to bury everything.

Sun Under The Laws

In some places the drifting snow has accumulated to the extent that catenaries that one could walk under with ease in the summer are near buried. The result? A lot of digging. Interestingly, catenaries are named after the mathematical curve they approximate, which is in turn described (almost circularly), as the curve described by a hanging flexible chain supported at both ends. I had assumed naively that they were parabolic curves but at least Galileo made the same mistake. See here for more of the maths.

Jim Raises the Flag

To celebrate the sun's return, the Union Flag is hoisted to fly above base again. Jim as the youngest winterer, as opposed to the lowering of the flag at sun-down by the eldest member of base, had the responsibility this time round. In contrast to the tattered, wind-frayed relic that was taken down in May, a new one is hoisted and will have to last a battering from the occasional storms until next sun-down.

Changing 'Dozers in the Garage

Sunnier days does may mean longer days to work outside but it does not necessarily mean warmer days; there are still plenty of times when even the most hardy 'dozer will refuse to start, usually when its around -40°C. The cold weather takes its toll even on these sturdy machines, which has meant a lot of work in the garage for Mat (Vehicle Mech) along with pressure to get out into the field, particularly for science projects, which involves defrosting and servicing vehicles that have spent the many months of darkness stowed away on the northern end of the container line.

Flying The Blimp

One of the most obvious additions to the science program since the sun has returned is a new building on base. The weather haven is little more than a big tent housing the Metbabe's blimp, a large helium filled mini-airship from which, when launched, dangles an array of measurement kit in Blue Peter fashion.

The Moon Shines on the Ice Cavern

The excitement behind the blimp is that it is used to study an atmospheric phenomenon which occurs here once the sun returns- Ozone Depletion Events. Though Halley has an important place in the discovery of the 'ozone hole', this involves ozone at a high level in the earths stratosphere (15-25 kms above the ground), which is where most of the earth's ozone is found. On the other hand Ozone Depletion Events involve the ozone found in the low troposphere, which in turn is the lowest region of the earth's atmosphere.

Losing Contrast in a Blow

Ozone depletion takes place over the course of a few days at a time and is thought to occur as sea ice forms out on the Weddell Sea and in the presence of sunlight. It is interesting scientifically as the loss of ozone effects the local temperature but also contributes to the larger picture of the physics, chemistry and meteorology of the boundary layer (the lowest part of the atmosphere), which is one of the major areas of research on station. Understanding of what happens in this part of the atmosphere at Halley is applicable not only across the Antarctic but also around the world.

Bringing a Sno-Cat In After the Winter

It is difficult to convey quite how complex it can be living as an isolated community in such a hostile environment, for out of the 18 people on base only 8 are directly involved with running the 24-hour science experiments and data collection. The rest of us are in some way supporting the science, not that this leads to a clear distinction at Halley; everybody is involved in some way in the general work around base that allows us to live here and on the other side, from helping with flying the blimp to doing weather observations overnight, most people participate in the science side of life on base. Though clearly one could not exist without the other.

Hauling Jerry Cans To Be Repaired

Of the other ten people on base, five belong to Technical services and bring the skills to keep the vehicles, generators, plumbing, electrics and building running. That leaves a base commander, communications manager (a successor to a radio operator who looks after both the radios and part of the computing on base), chef, field assistant and myself.

Sune Fixing Nansen Sledges in the Laws Corridor

Though as the base doctor I have a relatively quiet role, apart from running a couple of science projects of my own and dealing with the rubbish that we generate, it means that there are plenty of people who need a hand doing jobs around the place. As a result there is plenty to keep me (relatively) busy.

Jacking the Laws Legs With Jim

One of my monthly jobs has been to help Jim (Steel Erector/ Carpenter) survey the three main platforms. The wind, snow accumulation and weight of the platform all mean that the buildings warp slightly on their legs, particularly the Laws. As a result throughout the year between the two of us we have attempted to try and keep the platform level on its legs. It rapidly gets cold suspended 5 metres off the ground handling cold steel at -40°C, while jacking the building upto 10cm at a time either up or down a leg.

In the Darkroom

Along with helping Sune (Field Assistant), with his maintenance of all the field kit ready for the science projects and second round of winter trips which start in a fortnight, there are other skills to perfect that I would not usually need to carry out anywhere else in the world. One of these is radiography (taking X-rays); along with the various other parts of training before we came away, radiography featured heavily, for as well as taking x-rays , I of course have to process them as well.

Bivvying Outside For Ant's 30th

I had not realised how similar x-ray (radiograph) processing is to black and white film and negative development. Fortunately, one of the smaller rooms on base is turned over to a darkroom from a time when black and white photography and slide films were all the rage. I and a couple of other people occasionally put through a couple of rolls of black and white films but given the ease and availability of digital photography, the darkroom, though still necessary for x-ray development, is used less and less for film and slides.

Kirsty Cuts Into Her Hello Kitty Birthday Cake

Of course August and September means a glut of birthdays and I have made a succession of heavily iced cakes. However, Ant (Chef), keen as ever to go one better and preferring not to go for the traditional Saturday night celebration in the bar, came up with the plan for a surprise ice cavern to celebrate his 30th birthday.

Ant's Ice Cavern
Featuring the digging team (L to R Ant, Dean and myself)

So a crack team of diggers were enlisted and sworn to secrecy, such that over the course of two days the three of us managed to shift enough snow to build a cavern into the wall of the Drewry windscoop, large enough to fit nearly all the base. Its amazing how warm snow caves and similar structures can be especially with a few candles burning to lighten the darkness.

The Inside of the Ice Cavern
Wrapped up warm nonetheless

To celebrate the actual birthday a handful of us agreed to sleep out in bivvy bags within the perimeter. (Bivvy bags are little more than plastic sacs designed to accommodate a sleeping bag and little else- apart from here a sleeping bag means also at least four layers of insulating material including a large sheep-skin rug between the bag and the ground). The idea of sleeping underneath the stars is beautiful but despite the clear view we had that night, I think most of us remember more for how little we slept that anything else!

Entering the Ice Cavern

Tuesday, August 07, 2007

Et lux in tenebris lucet

The Light Shines in Darkness
(Click on photo to enlarge)

As the bad weather finally cleared, all of a sudden it became clear how close we are to seeing the sun again. The winds settled and the thick layer of low cloud peeled back to reveal the beautiful 'mackerel skin' rippled appearance of altocumulus that makes the most beautiful skies; with it came light that has been so lacking for the last few months.

Celebrating the Return of Daylight

The northerly glow in the top picture is about as bright it got but the quality of the light is almost impossible to capture photographically. What is also difficult to convey is the appreciable excitement and burst of energy, on a personal level and around base that accompanies the gradual exit from persistent darkness. If nothing else it makes working outside a lot easier, since there is no need for torches in the middle of the day.

Sune Manhauling Jerry Cans

It also means that when kite-skiing large sastrugi are spotted quicker as you approach. Kite-skiing or boarding is one of the most popular sports on base, with at least half of base owning a kite. Unfortunately, my enthusiasm exceeds my technical ability but it makes a change from cross-country skiing. Either on skis or a snowboard, you attach yourself to a large kite- usually around 7-10 sqm in surface area much larger than a typical stunt kite- via a body harness and then by moving the kite, like a sail through the wind, generate lift to power you along.

Kite-Skiing On the Edge of the Perimeter

Regardless of the weather, one of the jobs of the Met (Meterological) team- the Metbabes- on the Simpson is the launch of a weather balloon, seven days a week. The balloon is filled with helium from the warmed stillages in the BART caboose, which is one of the blips on the horizon between the Laws and the Simpson. Hydrogen was formerly used and is still used in some parts of the world but its highly flammable nature means that helium, though more expensive, is a LOT safer! Officially BART stands for Balloon And Radiosonde Terminal but as it belongs to the Simpson, well...

Kirsty Filling the Balloon Inside BART

Attached to the balloon is a radiosonde, which continually sends back data as it rises high into the atmosphere including temperature, pressure and humidity, along with GPS data which allow calculation of wind speed and direction. Some reach as high as 25km (15 miles) in the atmosphere before bursting, at that height they reach the size of a double-decker bus as the helium expands. The data is logged on the Simpson before being sent off to the Met Office in Exeter, where it is fed into the models that provide daily weather forecasts for around the world including the UK, as well as providing data for the long-term monitoring projects that form part of the research here.

Launching the Weather Balloon from BART
The Simpson is in the background- look how light it already is at 11am!

The balloon is released at 11am daily, so that it is in the atmospheric area of interest for midday. They disappear fast, rapidly becoming small specks in a large sky and though visibility can be fantastic, within a few seconds they are lost to the naked eye. Round the world there are almost a thousand balloon launches at close to midday, all of which collect information which is then shared globally for both forecasting and climate research.

Pulling An Empty Pulk

The return of the daylight also means the end of the light box study, most people who were involved are only to glad to not have to be woken to an hour of bright light early in the morning nor to have to collect every drop of urine for 48 hours, as I have asked on a fortnightly basis during the darkness. While questions such as 'A does not precede B - BA: True or False' will not be missed. The return of the light means plenty of digging and for me the start to sorting out the study data.

The Tractors On the Old Drewry Windtail