Extreme Science: Drilling Holes in Arctic Sea Ice
This is the first in a series of blog posts from scientists taking part in the third-annual Catlin Arctic Survey
It’s my second time working on the Catlin Arctic Survey, so I feel I know my way around. It’s amazing how quickly you get used to the living conditions. Hanging out our sleeping bags after breakfast to defrost and get rid of all the ice that has formed from our breath during the night takes a good 15 minutes; dragging a sled to “work” every morning and chipping ice out of a hole takes another half hour.
Digging a sample hole through the ice. Credit: Catlin Arctic Survey.
We’ve been sampling through holes cut in the sea ice (which is about 1 meter and 60 centimeters thick). To make them, we had to drill through the sea ice to get to the seawater below. We started drilling using a motorised Mora augur down to about 1 meter 30 cm and then chipped out the remaining ice using ice chisels. As soon as we puncture through to the seawater it begins to gush through the gaps and fill the holes. Within a matter of minutes each hole fills with seawater. It’s hard manual work in the cold conditions (Our first hole was made when temperatures never warmed above minus 35ºC). But hot work too, so sweat starts to freeze when you stop, leaving a layer of frost on my jacket. It may be tough, but working in these conditions means we get to eat as much chocolate and drink as much tea as we like.
It has to have its rewards.
In the first hole we have set up an instrument to measure current speed and direction of flow. It’s a device called an Acoustic Doppler Current Profiler (ADCP) and it hangs just below the ice taking continuous readings of the seawater as it passes by. It’s giving us an idea of some of the physical properties of the seawater — the different currents that flow through the area, any tidal regimes or vertical flow. We’ve put a tent over this hole, just to help slow down the speed at which it refreezes. Every day we have to chip out the inch or so of ice that has reformed.
We put a geodesic dome tent over this hole, which took 5 of us to put up as it was quite a large size. It also made for quite amusing photos as we lifted the tent over the hole and into position…
Our second hole is used every four days or so to take samples of seawater from different depths. We’re also deploying instruments that make profiles of the seawater temperature and salinity, as well as light profiles and measurements of fluorescence (an indication of the different particles present in the water — either live organisms, like phytoplankton, or just organic matter that has been released and is floating around in the currents).
Making a sampling hole takes hours of hard drilling work through tough ice. Credit: Catlin Arctic Survey.
Today we drilled another hole in the sea ice through to the seawater below. This was our biggest hole yet. It’s an impressive 1.8 m long by 1 m wide and the sea ice is about 1.7 m thick. This ice hole is a special one because it is going to be used for running experiments rather than just routine sampling of the seawater. The hole took about seven hours to make, so it’s been nonstop all day. Like the other holes we drilled, for the first meter or so we used a motorized ice augor to create about 25 smaller holes which we then chipped between to knock out big blocks of ice. Once we were through to the next "layer" we chipped away the remaining ice using ice chisels.
One of the reasons we need a hole like this for experiments is that we need to keep the plants and animals that we are interested in studying in the right conditions. The air temperature would freeze them straight away and it’s too difficult to try to keep seawater cold in our laboratory tents. So the best place for these creatures to be is in the sea. So we can capture some organisms, or sample seawater, and put them in bottles. In these bottles we can look at how the creatures are behaving, take measurements or even change the chemical conditions. We then hang these bottles through our ice hole into the seawater below so that the creatures are kept at the right light and temperature conditions.
For now, while my body is aching, my stomach is full of dinner and chocolate, and I’ve just watched a gorgeous sunset. I’m really just looking forward to curling up in my three layers of sleeping bags with my hot Nalgene bottle and sleeping through the clear light skies and -28ºC temperatures.
Helen Findlay has a doctorate in biological oceanography and works at Plymouth Marine Laboratory (PML) in the United Kingdom. She is currently one of nine scientists working at the Catlin Ice Base off Ellef Rignes Island on the edge of the Arctic Ocean north of Canada, where she is studying ocean acidification and the ability of organisms to cope with a changing environment.