Thursday, September 13, 2007

The Last of the Aurora?

Sunrise Behind the Laws

As sunlight now dominates the day and the temperatures gradually warm, it is hard to remember the last day when it was well below -40°C. However, the nights still remain dark and there is even still the occasional auroral display, though the problem is not their rarity but the cloudy skies obscuring the light.

Aurora Over the Drewry

Difficult to capture with still photography is the activity of the aurora as they flicker across the sky and their dynamic nature. Moreover, there is the increasing temptation, when awoken from deep sleep by a knock on the door, as the night watchman has seen a glimmer of light on the horizon, to turn over and fall back asleep. You do so at your peril and invariably miss 'the best display of the winter' so far when it is discussed at lunch the next day.

Moving Auroral Display

The GIF file above is of 5 shots taken over the course of several minutes, long enough for the stars to appear to move across the sky. Even on cloudless night skies without aurora there is plenty to see as the Milky Way cleaves a bright rift in the sky.

Scorpius and the Milky Way Above the Drewry
Inset: the constellation of stars that make up Scorpius (the brightest 'star' is Jupiter), its tail and sting sit deep in the Milky Way

Halley was built as it lies in the auroral zone, which makes it an ideal place to study the upper atmosphere and the interactions between the sun and the earth as solar particles bombard the ionosphere. Most of this science is run from the Piggott platform, while the other major science platform, the Simpson, runs the experiments studying the lower atmosphere down to the snow surface.

Sunrise With A Sun Pillar and the Simpson

The Simpson houses what has to be the most famous bit of science kit on base and as such one of the most exciting- the Dobson spectrophotometer. It was observations made at Halley over the 50 years the base has been here that led to the realisation in the early 1980s that ozone over the Antarctic was at much lower levels during the period of August to October than would be expected, a phenomenon that has come to be known as the ozone hole.

Dave Works the Dobson

Ozone is measured in Dobson units after an Oxford meteorologist from the early 20th century, who was one of the first to recognise the presence of the ozone layer and design an instrument to measure the level of ozone in the atmosphere. The atmosphere, if considered as a vertical column directly up from any point on earth, contains around 300 Dobson Units (DU) of ozone which would be the same as a layer of ozone 3mm thick if the whole column was brought down to the earth's surface.

Andy On the Laws Windtail

Most of the atmosphere's ozone is high up in the stratosphere peaking about 25kms above the surface. It is considerably less dense in the lower atmosphere but ozone here is the subject of distinct research at Halley. The levels of stratospheric ozone fall to around a third of their background levels at around this time of the year, due to a reaction which requires the sun's energy but is catalysed by the products of chlorofluorocarbons amongst other gases, such as nitrous oxide. It is all localised to the Antarctic due to a combination of cold temperatures, particular weather systems and sunlight.

The Laws In Snow

The most relevant local effect is the increased level of UV exposure. Antarctica is already high-risk for the damaging effects of UV but this is exacerbated with sunburn and snow blindness as particular hazards. They are however fortunately rare as everyone uses liberal amounts of sunscreen and sunglasses.

Sunset Looking North From the Laws

Though satellites now provide much of the information with regard to fluctuations in ozone levels, these still have to be calibrated and this is an important part of the work of this and other spectrophotometers dotted around the world. Though there are a couple of instruments which are rotated between the UK and Halley to allow accurate calibration, it is pretty exciting to be in the presence of an instrument that is part of a continuing experiment and observation which has had such a profound effect on the world we live in.

Manhauling to the Laws From the Containers

For though the Montreal protocol has been highly effective in limiting the release of chlorofluorocarbons, the realisation that the ozone hole is a product of man on the environment was fundamental in our awakening to the damage we are doing to the earth. Interestingly, the US Regan administration strongly supported the efforts to reduce CFC production; given that the BAS paper was published in 1985 the protocol came into force a rapid 4 years later. It has been hailed by Kofi Annan as " Perhaps the single most successful international agreement to date ...". This is in stark contrast to other attempts to deal with our effect on the environment, such as the Kyoto protocol, where such support is lacking.

Wrapped Up Warm
Photo thanks to Dean Evans

The most remarkable part of the last few weeks for me has been my 30th birthday. Unfortunately, not a good enough day to visit the penguins but with some decent weather I found myself hanging off the legs jacking the building again.

Celebrating On the Day

The advantage of reaching a small milestone is that you are allowed to celebrate it at least a couple of times and as such, as well as having the traditional fancy dress party on a Saturday night (in my chosen theme of London tube stations), a few hours of digging resulted in a small ice bar to have a few drinks on the day itself. It seemed a rather cool idea to make glasses out of frozen ice at the time, unfortunately at -35 the ice froze to the lips of anyone who tried it; I am still nursing the wounds.

London Party

I was released from my cake-making duties this time and was treated to a spectacular creation by Ant and Tamsin featuring a large proportion of the base's supply of food colouring. With the first of the post-winter trips already off base, the whole place seems a bit empty particularly at meal times and in the bar. However, it is a glimpse as to how next year's team will feel as there will only be 11 of them compared to the 18 of us on a good day.

Blowing Out the Candles

Around and about, there is plenty of work to be done, particularly as almost all of the science is being put on hold for a couple of years while Halley VI is being built, which means packing up both the science platforms. There is an Augean task of clearing paperwork and instruments that have built up over the lifetime of Halley V. Bad weather has also had its toll on science kit including destroying one of the blimps that was being used to study ozone depletion in the lower atmosphere.

Clearing Out the Simpson
Dave gets to work in the Met lab

It is not only the science platforms that need getting ready for the summer, given the unusually large number of people intended to be on station during the building period that will encompass the whole of the summer (and several summers hence), there is a lot to be done to start getting the whole base ready to deal with housing, feeding and looking after the 120+ people will swamp what has been our home for most of the year.

Sune Getting Field Kit Ready

Nonetheless most of the evening activities which started shortly after the departure of the last ship have continued, with people touting their various expertise in French, Spanish and German to small groups in weekly language lessons. In addition, Thursday and Friday evenings on the platform are dominated either by the samba band or Halley's own rock band rehearsing. Many people take refuge either on in outlying building or nurse a pair of ear defenders, for one of the great flaws with all main platform is the relative absence of sound-proofing in most of the walls. Conversations, let alone loud drumming, can easily be heard through many of the thin partitions.

Samba Drumming to Celebrate the Notting Hill Carnival
6 of us work the drums and the lens- photo thanks to Dave Evans

As the winter dwindles away thoughts turn to plans for returning home. The Halley Doctor usually spends the Halley summer (the period from the first call of the RRS Shackleton at Halley until the last call), as the ship's medical officer while it is in the Southern Ocean, while the incoming Halley Doctor leaves their job on the ship, having provided medical cover all the way from the UK, to cover the base at the earliest opportunity (as I did on January 1st this year).

Learning to Splice
Eye-splicing skidoo link lines for field work

With the increased number of people on station this summer and a large amount of building work, there will instead be two of us on station for the whole of the summer with another doctor covering the ship. As a result, I will either fly or sail out of here sometime in March at the end of the season, arriving in Cape Town in either March or April time, dependant, as ever, on a whole host of factors. Notably, staying on station for the summer has had little effect on when I am likely to return to the UK as compared to working on the Shackleton.

Mourning the Destruction of the Blimp
L to R: Brian, Dave Tom, Alex, Tamsin, Kirsty and Jules

It will be exciting being here over the summer, as not only will the new station start to take shape as it is built here before being towed (in future years) to its eventual home but there will also be considerably more science projects in the field as compared to last year. As ever, it will be busy but I suspect very different from last summer.

Sastrugi At Windy Bay

Tuesday, September 11, 2007

Escape From Station

Emperor Penguin and Chick

For at least the last four, if not five, months our lives have been confined to our small part of the Antarctic circumscribed by the perimeter of empty fuel drums. Apart from the seventeen other people on base, none of us have seen another living thing since a pair of Wilson's Storm Petrels were seen fluttering around one of the cabooses six months ago. That has all changed in the last few weeks.

The 4Km Marker on Skis

The rapid return of daylight, the quantity of which increases by 20 minutes every day, has meant that it has become feasible again to ski a short way off base to the 4km marker. Its name is confusing since it acts as a marker for the planes navigating a descent onto the skiway and as such it is probably closer to 6km from the Laws. Though not a particularly taxing 45 minute ski each way, the excitement comes from heading off into the Antarctic, with nothing but ice as far as the eye can see, met by a cloudless azure sky. Though it is a featureless trip, punctuated only by sparsely dotted flags to mark the way, the thrill comes from the escape from the station and the steady rhythm of skis cutting across sastrugi.

More Emperors

However, better was yet to come. Halley is fortunate that it lies close to one of the 50-odd Emperor penguin colonies dotted around the continent. There are only two species of penguin found in the Antarctic itself- Adélies and Emperors- with the latter found nowhere else. The colony lies at Windy Bay (see map), some 20Km off station to the north-west and trips out to see them is one of the highlights of the year here following Midwinter.

Penguin Tracks on the Sea Ice
Footprints are often scoured by the wind such that they stand proud of the snow

The penguins have been out at Windy since late April to May, when they mated and subsequently the males have been incubating the eggs through the darkness. It is not hard to imagine the miserable weather that they have endured as we have lived through the same period, but to survive it almost stationary whilst protecting their single precious egg from the icy ground, without the benefit of central heating and regular warm food is all the more remarkable.

Yet More Penguins

Just how poor and fickle the weather can be is demonstrated by attempts to visit the penguins. I was fortunate to be scheduled on the second day trip to see them about 10 days ago on a Sunday. The possibility of a trip requires the combination of warmish temperatures (that is warmer than -35°C-otherwise vehicles will not run), good visibility and low wind. Unfortunately the latter two tend to be associated with poor cloud cover, which in turn is associated with warm temperatures. It requires a special day for all three features to come together successfully.

Attempt No 1- Restarting Very Cold Skidoos
Sune and I attempt to pull-start skidoos at Windy after a rapid drop in temperature (photo thanks to Dave Evans)

On the first attempt, the weather was too cold to take a Sno-Cat, which will refuse to operate below -30°C, so we took skidoos. However, the temperature plummeted beyond an acceptable operating temperature even for the 'doos and we had to turn back at the cliff edge in sight of the colony.

Attempt No 2- Heading Back to the Laws
Loss of contrast puts an end to the second attempt

The second attempt looked like reasonable conditions but a rapid deterioration in contrast meant this time we did not even got off base. Despite having all the kit packed and ready to go, it takes at least a couple of hours to warm vehicles, lash sledges and general faff, so even an aborted trip is not without an investment of time.

A Young Chick

Fortunately, it was third time lucky; given that I have been on nightwatch again, I was roused from my bed after half an hour and despite the lack of sleep it is not easy to turn down such an opportunity. A couple of hours of faff and a ninety minute Sno-Cat ride later, the five of us found ourselves on the cliffs at Windy able to see the colony as a dark line a couple of kilometres out on the sea ice but also could hear the gentle chatter of a couple of thousand penguins.

Dean Prepares to Descend the Sea Cliff

The cliffs stand 20 to 30 metres above the sea ice and the previous trip having an identified a suitable crevasse free area, meant an easy rope-assisted descent onto the ice. Even though the ice extends nearly a thousand miles off the continent at the moment, it is punctuated by leads (open water) and thin pressure ridges, which amongst a multitude of other hazards, make it particularly treacherous. (See here for a glossary of terms associated with sea ice.) The ice at Windy is at least second-year fast ice, a couple of metres thick and so should be as safe as any sea ice but we still carry a variety of safety kit and travel unlinked.

Heading Out On the Sea Ice
Penguins form the thin black line on the horizon

The more adventurous penguins, so unused to seeing any other creatures and sharing a mutual curiosity, started to wander over the moment we were on the ice. Without any predator on the ice, they will quite happily approach to investigate further. As a result, if you remain still, the more inquisitive will come as close as a couple of metres, even though we keep a much greater distance between them and ourselves so as not to disturb them.

The Colony At Windy Bay

In some places the colony can still be seen huddling together for warmth, it may be that some are still incubating eggs. The females meanwhile are out at sea feeding; the leads mean that they do not necessarily have to walk the thousand miles to open water but they head away from the colony for a couple of months through the darkness.

Huddled Together For Warmth

Through the same period the males penguins have guarded the eggs on their feet, which bear large thick pads which protect them from the ice. The eggs are also protected from the cold by a large parental pouch which in turn is inhabited by the chicks once they hatch.

Penguin Feet

In a further contrast to our cosseted existence the male penguins lose almost half their body weight as they have not fed for several months, as opposed to Ant's vigorous attempts to fatten us up with his top notch cooking. The weight disappears as they burn fat to keep themselves warm and they initially feed the chicks with secretions from their oesophagus while waiting for the females to return with stocks of regurgitated fish.

Feeding Chicks

A couple of hours sitting stationary, watching and photographing, means the cold starts to bite into the excitement and it was time to return. Hopefully, there will be further chances to visit them over the next couple of months, particularly on the forthcoming post-winter trips.

Lashing the Sno-Cat
I pack the kit up before heading home

Meanwhile, back on station I am currently nightwatchman for the week but with the first flight due to arrive in less than two months there is a lot of work to be done around base. The start of the Halley VI build (the successor station to Halley V), means that the summer is going to be busy- there is plenty to get straight before then.

Yet Another Penguin Shot