One thing that is very noticeable down here in the Antarctic is how dry the air is. It is in fact the driest continent on earth.
Warm air can carry a lot more moisture than cold air. This moisture
is actually invisible vapour (gas). When you breathe out on a frosty day, the
warm moist air from your lungs becomes chilled and forces the water to condense
into tiny liquid drops which appear as a cloud. This phenomenon
once allowed me
to appear as if I were smoking a cigarette at school (it was a plastic
imitation) which successfully ‘wound up’ my teacher without leading to any painful
consequences for myself or my lungs.
On Planet Earth – we could compare the hot and humid equator
with our lungs breathing out. Due to the warmth
there, the air expands, becomes
less dense and rises. As it rises it expands further and cools, having to release
its moisture as rain (hence the tropical rainforests) and then flowing away
towards the North or South as high level dry air. After a somewhat involved
journey which may include sinking to the surface and rising again, this air
finally reaches one of the Poles eg Antarctica,
where it is now very cold and sinks to the surface. It has nowhere to go but
outwards, blowing away in all directions from the centre of the continent. The
dome like profile of the ice sheets also encourages these dry cold winds to
blow faster and faster towards the coastlines. So it is the windiest continent
too.
Here at McMurdo, we are told to look out for banks of low
cloud (which is the windblown surface snow) looming up from the South - a sure
sign of bitter winds. I took the second and third photos last year - this year has been relatively quite so far...
So, if the air is so dry, and it therefore snows very little (a very few centimeters a year on most parts of the continent) how come there is about 4000 meters of snow and ice piled up over the landscape? - It has accumulated over many thousands of years and has never melted away due to the temperatures staying well below zero.
So this was all to tell you why we have to drink so much water continually through each day to avoid dehydration and a dry throat. I have just done a quick survey of 20 people working near by to me in the ANDRILL offices. Of the total, 17 of them had a bottle of water or drink beside them, and three did not. I was actually quite surprised at these three. On further enquiry I learned that each of them do regularly drink, but there mugs or bottles were just temporarily somewhere else.
Another related thing is that because of the dryness, static
electricity builds up very quickly. Whenever I take my jacket off and
hang it onto a metal hook there are usually crackling noises and an
electric shock. A great way to start the day!
Things are changing slowly at McMurdo. The population has now reached just about maximum capacity with about 1200 people on Base. This is partly because the Summer contingent that are headed onwards to the South Pole Station are unable to travel due to exceptionally cold temperatures. They are still well below -50 degrees at the Pole- the threshold below which the Hercules aircraft are unable able to land safely.
Another
change is that the sun has climbed a bit higher in its path through the sky and
no longer hides behind the horizon at night. It circulates through the sky,
skimming the horizon to the south at midnight, and traveling up to a point
about 23.5 degrees higher when it gets to the opposite (north) side of the sky
at noon.
There is a convenient sundial on the base, which I can now use 24/7 to tell the time (if I want to go outside and look!). Look for the shadow to find what the time was when I took the photo of it last night.
If you look carefully at the picture there are a few
interesting points to notice.
The shadow producing stick (gnomon) is leaning at an angle of 12 degrees towards the South. If we were at the South Pole itself it would be pointing straight up, as the sun would be traveling more or less horizontally around the sky from right to left. Because we are instead at latitude -78deg, we are 12 degrees north of the South Pole, and the axis of the suns daily path is tipped by that amount towards the South. So it’s simplest to tip a sundial in the same way to keep the gnomon lined up with the Polar Axis. That way the interval between each hour will stay simply 360 degrees/24 hours = 15 degrees
The letter GN and GW stand for Grid North and Grid West which represent the directions depicted on a map of the area. Doesn’t it seem a bit odd that Grid West should be pointing in almost the opposite direction to True West? I had to think about this for a minute or two. If you look at a map of Antarctica, the reason for it may become clear. Have a go and email me your ideas if you like!
An exciting day today!
We saw the first cores of the sea bed. These were retrieved by pushing a hollow core barrel out of the steel tube (which is called the sea riser). This riser has been dangling 940 meters all the way down from the surface to within a few inches of the sea floor. As it moved slowly from side to side with the tides, the drillers pushed the core barrel out under high pressure to grab some length of core from the upper layers of mud.
The very first of the cores were used for analyzing the chemistry of the water locked within the spaces between the particles. This process tells the scientists about the chemical processes happening near the surface, and how conditions are for living organisms. By analyzing the oxygen isotopes in the pore water, it will be possible to tell whether there was once a thick ice sheet that actually completely froze down to the sea bed (a higher proportion of relatively light isotopes will suggest a glacial rather than oceanic origin for the water). This would only happen if an ice sheet were big enough to push out all the sea water from the area. However this pore water analysis involves squashing the water out of the cores, and so the core is basically flattened in the process.
These six new cores we saw this morning were the first ones
to be left intact.
Remember that the most recent part of the sediment has been
laid at the top of the pile, so as you go down the core you are going further
back in time.The cores were quite short – the longest about half a meter,
but it is thought that that depth represents about 20 000 years of time –
taking us right back into the peak of the last ice age!
In the cores we could see different layers. There were fine
grained muddy layers, with quite a few larger pebbles lodged in them. These dropstones
as they are called, are the boulders and pebbles that have been scraped off the
land by the glaciers, and then taken out to sea before being dropped to the
depths when the ice melted and released them. They are a classic deposit found
below ice shelves or areas of ocean that contain icebergs.
There was also a turbidite layer – this is a layer of
sediment deposited by a submarine avalanche flowing off a nearby underwater
slope. By carefully studying the particles, the scientists will soon be able to
tell where the avalanche came from. It is made of volcanic fragments, which can
be analysed to find which nearby volcano they belong to.
The upper part of the cores contain a proportion of tiny fossil plants (diatoms) and parts of silica sponges, revealing the transition to more open water, where the sunlight was able to penetrate because the ice has retreated. One of these diatoms is called Fragilariopsis kerguelensis (Try saying that that ten times with your mouth full!) The amazing thing about this little plant is that it has been discovered in the North Atlantic having been transported by deep ocean currents moving from Antarctica via the Pacific and Indian oceans!
It was great to see the way that different information is already starting to build possible elements of a climate history...
The
drilllers and scientists out there at the drill site are carefully
setting up the initial extraction of samples of the soft surface
sediments. This is a different and more complicated process from the
hard rock drilling that will happen when the deeper layers are
reached. A maximum of three meters of the soft material can be
extracted at a time - and the process is done in a different place for
each additional three meters of depth to be sampled. At a certain
point, when the sediment gets harder (probably within 9 meters depth)
the drill bit will be changed to a rotary cutter and progress will
speed up. This will be a big moment, and will jolt the whole machinery
of the science analysis teams into action. There will be day and night
shifts with most people working atleast 12 hours each day. It is
absolutely fascinating to learn about the technical intricacies of how
the technicians feel and test their way blindly into the sea floor one
kilometer below them
So at the moment there is a
relatively quiet waiting time, with everyone preparing in their own
ways. Yesterday several of us went for a walk up the 5km (3 mile) Hut
Point Ridge track. This is on the opposite side of McMurdo to
Observation Hill. It was a windy day, so we were well wrapped up. To
protect my face I had on my insulated face shield, neck gaiter,
windproof fleece hat, ski goggles and ECW hood.
We
set out first for Scott's Hut - a short walk out of the base. Then we
started to climb the ridge above. The wind was very strong in places,
and by the time we got to the flatter area at the top there was a
steady gale blasting snow across the ground.
Behind
us there were views across the sea ice, past the air runway to the
Transantarctic Mountains. Ahead was the huge white dome of Mount
Erebus, to the left we could see along the coastline of Ross Island,
and to our right and below was McMurdo Station with Observation Hill
and the distant Ice Shelf behind.
The
track veered around to the right, past the satellite receivers of
Arrival Heights (a restricted area we had to stay clear of) and back
down to the creature comforts of "town".
After dinner, I did the walk again, this time in the opposite direction, the wind was calmer and the views impressively expansive.
As you can see from the
photos the landscape is mainly black or white - well at first sight
anyway. Perhaps strangely, the absence of colours actually makes you
more sensitive to what you see. I find myself noticing subtle shades of
white, grey, yellow, orange. It is as if your eyes become hungry for
differences in texture and colour that would normally not stand out at
all. I have quickly and happily realised that the views never look the
same twice.
Julian
This
morning I set out for the short walk up observation hill just above
McMurdo Station. It is one of the few walks for which it is unnecessary
to sign out from the base.
I
wrapped up very warmly, with several layers and my big ECW (extreme
cold weather) jacket over the top, ski goggles and a face mask that
protected me completely from the wind. At the entrance to the main
building I strapped on some attachable studs to give my feet extra
grip, and off I went.
There was quite a strong breeze blowing as I left Mactown behind me and clambered up patches of snow lying in areas of gravel and volcanic boulders. Up higher the ridge became more distinct, and the cross wind was blowing snow sideways. I soon found out that to the right of the ridge the drifting snow was much harder to climb than the crest itself which was swept clear and had a layer of good hard snow for my studs to push in to.
Soon
I was at the top, with a view across to Scott Base, the Ross Ice Shelf
with the ANDRILL drill site visible in the distance. Behind me was a
great view of Mactown and the sea ice airfield.
Well at last we are here. It has been a very busy and exciting time, and there is a lot I could describe.
We flew from Christchurch in a C17 which is a huge US military plane. Very spacious and faster than the Hercules I traveled in last year. In only 5 hours we landed on the frozen sea ice that is used as an airport for McMurdo Station and the smaller New Zealand Station, Scott Base
McMurdo station has over 900 people staying at the moment. It
is a strange ugly settlement.
Looking across the central area you see large
concrete and metal buildings, linked by telegraph wires. When the noise of the
freezing wind stops for a while, you hear the sound of humming from every
building, - and large trucks and four wheel drive vehicles cruise slowly passed
or stand waiting with their engines endlessly running. People are few to be
seen outdoors - they pace purposefully from one building to another. There are
over 100 buildings; each has a number, but nothing to indicate its use from the
outside. Everything from a sea water distillation plant, a chapel, hydroponics
greenhouse, a shop, machine storage sheds and workshops, and 11 accommodation
blocks.
We are settled into our accommodation units and have been briefed about everything from outdoor safety, environmental care, helicopter travel, recreation possibilities, tents, lighting stoves, and water conservation.
Last night I went for a walk at 1am. The sun actually sets
at this time of year at about midnight, and rises again at 3am. It wasn’t dark
at 1am though, more like a colourful sunset, which quietly and unnoticeably turned
into sunrise without a dark time in between. Before breakfast this morning I
went for a short run from the accommodation block to Hut Point – about 1km away...
The temperature was about – 25˚C and with a strong breeze the wind-chill made
it about -40˚C. It was good to get a feeling for how cold that is! Especially
when running into the wind. Parts of my face that were not covered by my neck gaiter,
2 hats, jacket hood and ski goggles were instantly in pain. These conditions
are by no means described as “bad”. They are “weather condition 3” (i.e. normal)
as opposed to condition 2 or 1 which become progressively harsher. No-one is
allowed to move outside in condition 1, which means that you are stuck in
whatever building you are in, for as many hours or days that the storm lasts! Thankfully
that doesn’t happen too often, but I do think i might get a stash of food into my room...
Here in New Zealand we are having a day of
cold southerly winds and rain. This blasts straight off the Southern Ocean -
the only thing between us and Antarctica. It
makes me think of that cold white wilderness where these winds must ultimately
come from...
My snow caving expedition was a success. Thirteen of us slept under the snow.
It took about three hours to dig the snow cave, but amazingly, we had plenty of
room. It even felt rather warm! On the next day we climbed up the steep slopes
to
the top of Ruapehu and had a great view of the crater lake and clouds far
below us.
Well that was a few days ago. Tomorrow I intend to travel back up there again.
This time to do some skiing with my youngest daughter. It is to be our treat
before my absence
from home for two months. I’m hoping that the weather will
improve and that there will be a pile
of fresh snow for us, as well as perfect
calm and sunshine!
After I return from the mountain again I will have to get more serious about
packing and other final preparations. I will fly to Christchurch and meet the rest of the team on
17th October, ready for our scheduled flight to the ice on the 19th.
Thank you to all of you who have sent messages to me so far. I will be away fro
a few days, and can be back in touch on Monday.
cheers!
Julian
September 22, 2006
It’s quite something to be part of all this. But spending hours in front of a
computer screen seems a long way away from that bleak, wild, cold place that is
the reality of Antarctica.
So for now I am putting information together, spreading the word and planning a
cold night in a snow cave with some of my students this weekend. We will be
digging ourselves in above one of the ski fields on Ruapehu - our snow covered
volcano in the centre of the North
Island. That should be a
nice precursor to a visit to the coldest place on earth...
So, if you are reading this - do feel free to send me a message, introduce
yourself and ask any questions that you may have about Antarctica
and the ANDRILL project. I will be updating this blog more as the journey south
begins...
Cheers for now
Julian
Since the soft sediment cores were retrieved, there has been a lull in core extraction while the drillers have been repositioning the sea riser (steel tube down which the drill is operated). It is presently being pushed into the sea floor and is at about 17 meters depth. When the drillers are satisfied that it is well enough embedded they will pour a special cement down the riser which will flow out of the end and make a water tight seal to allow the continuous rock drilling to start. So we still expect to be waiting for a couple of days before we start to get into the routine of dealing with a daily batch of core for analysis.
In the meantime there has been plenty to do – people on the
day shift usually come into the lab and office area between 7 and 8 am. For me
the day usually includes lots of emailing, writing, organising audio interviews
with scientists, and a whole variety of other activities including meeting and
talking with a lot of people.
Each morning at 9.30 we have a science update meeting in which the latest news from the drill rig is described, and individuals give presentations about their work which is invariably fascinating
It is, for example, wonderful to be told in detail by Lionel
Carter of Victoria University in New
Zealand, how the Ross Ice Shelf
visible right outside the Crary Lab window, is one of the main physical drivers
of the world’s ocean circulation! It is hard to grasp that this is the largest
ice shelf in the world – about the size of Spain, and 800 km across. Huge quantities
of sea water circulate underneath it and become cooled by about half a degree
C before recirculating out to the open sea. Then, during the winter months, an
area of the surrounding Southern Ocean the size of the Antarctic continent
itself, freezes into sea ice about 1 – 2 meters thick.
As the water freezes it
leaves it’s salt behind – so the water just below the ice is now very dense –
due to its cold temperature as well as it’s very high salt content. In addition
there are areas of open water, called polynyas, caused by the freezing winds
blowing off the continent and pushing the sea ice away. These open water areas
are chilled further by the winds (down to about -2˚C – the salt content allows
the water to stay liquid below O˚C). As the surface water rolls down into the
depths due to the increased density, it is replaced by an upwelling current in
a continuing process. All of this super cold dense water eventually reaches the
bottom of the Southern Ocean, and slowly slides northwards, past New Zealand
and into the central Pacific. From there it goes on its world tour through the
Indian and Atlantic Oceans, gaining and releasing its heat, rising and
sinking, until it finally returns to Antarctica again, after perhaps 1000 years. 