Here is an English Translation of a transcript of the latest Podcast from the MOSAIC Website that is only available in German.
The Podcast was posted last Wednesday (January 22) at 5:57 PM on the MOSAIC Website (in German) - the recording itself was probably made 8. January
Instalment 11 – thick ice, four-legged visitors and slight frostbite
In the meantime, the team around the new leader of the MOSAIC-Expedition, Christian Haas, has accustomed itself to life on the ship and to the camp on the Ice Floe. In this instalment the Sea Ice physicist goes into detail about the composition of the ice and how it is continuously changing. Apart from this, Dr. Haas also reports on measurements made by other scientific disciplines and explains how an aircraft landing-strip is made on the ice. The continual decrease in temperatures and the ongoing polar night present further challenges for the members of the expedition. And, this week, the camp got another animal visit.
…..[Ed.: Just so that transcript readers don’t miss out on the atmosphere of the podcast they should know that it is preceded and ended by sound recordings of strong wind and creaking ice….]
Arctic Drift – The audio logbook.
Christian Haas: At the moment we are at 87 degrees 8 minutes North. During the MOSAIC expedition the ship this the most Northerly that the ship has been. [Ed.: According to the positions reported on MOSAIC webpage this would date the time that this recoding was made a being around 8. January]
Commentator: In the meantime, the leg 2 Team has adapted to arctic conditions. The crew around the new Expedition leader Christian Haas has familiarised itself with the Icebreaker Polarstern and the condition on the home floe. Dr. Haas himself is head of the Sea Ice Physics section of the Alfred Wegener Institute and can precisely explain what an ice floe is and why the ice in the arctic is constantly changing.
Christian Haas: we are always using the term “ice floe”, but everyone probably imagines something different under this term…and at this time of year, in the middle of winter, there aren’t really any, anymore. When the Polarstern arrived here at the beginning of October, it really was the case that there were individual ice floes drifting in the water. They were separated from each other by water or thin ice. But the ice and the ice floe formed a unit and could be regarded as a swimming platform. The MOSAIC ice floe had a diameter on the order of two to three kilometres. But since we have been here and the winter has begun, the whole area around us has frozen solid, so that one can’t make out individual ice floes, because the borders between them are not visible, except with the help of Satellite data. Nonetheless it’s the case that the ice floe isn’t a plate, it isn’t a simple uniform plate of ice, but, as before, it regularly fractures and is displaced by shear zones. Till now we have just had a lot of luck that such shear zones and fractures didn’t go directly through our camp but were some distance away. Just yesterday we made an exploratory tour with snowmobiles to the West and East and at a distance of about two to three kilometres in each direction we found tears and shear zones. With that we could say that the floe is two to three kilometres in size, but the Northern and Southern boundaries haven’t been found yet.
Commentator: The ice and the alterations in it are being constantly observed. Using different kinds of measurements it is possible to completely understand the displacement of the ice. Many researchers view these displacements as a danger, because they can lead to interruption in their research. Others welcome the possibility being able to observe and analyse them directly.
Christian Haas: The ship’s radar, that every 10 minutes makes an image of the surroundings within a radius of 5 kilometres, helps us a lot. When one looks at a time series of these images it’s like looking at a film of the ice movement. Most of the time the ice is stable, but sometimes one sees shear events, where, because of a difference in the extent of ice-drift in different regions, a part of the floe suddenly slides by between several metres up to as much as 100 metres relative to the other part. These zones produce tears and the formation new pack ice ridges.
Christian Haas: For most of our colleagues here the tears and the formation of pack ice ridges are seen as a hazard, because they interrupt research. But for us as researchers and for the whole MOSAIC project of course it’s an important process that we want to investigate. This is because we want to better understand why the ice in the arctic has declined so much during the last few decades and to find out what processes result in the ice becoming thicker or thinner. The growth of pack ice ridges, the deformation of the ice and the sliding of pieces of ice on top of each other is a very important process and can make ice much thicker than it would become through solely as the result of freezing through contact with the cold atmosphere. For this reason the sea ice researchers and remote sensing experts who are involved in our project are very thrilled to be able to observe such deformation events at first hand and to be able to see how the ice can continuously become thicker through floes fracturing and sliding on top of each other.
Commentator: In the meantime, the floe ice is circa one metre thick and has doubled in thickness since the beginning of the expedition in October. In comparison, the so called “pack ice ridges” are considerably thicker. To investigate them more thoroughly various instruments have been installed in the ice.
Christian Haas: We see here that some pack ice ridges are up to three metres high. Pack ice ridges are like icebergs, that means that roughly a tenth of appears above the surface and nine-tenth of them are under water. It follows that where there are pack ice ridges the ice can be 10, 20 or even more metres thick. We have observed this with our remotely controlled ROV, with which we were able to make sonar measurements of the ice depth and we have already found ice thickness of over 10 metres. In our last big action, we installed a number of instruments in some of these pack ice ridges. We call this the “Pack Ice Ridge Observatory” and we want to use it to observe on the one hand how the underside is eroded by currents and by the warmth that is present in the sea water and on the other hand how the pack ice ridges are frozen from above. In addition, we want to know how, because of their rough surfaces, they are affected by turbulence in both air and water and whether this is important for their growth or melting.
Most ice measurements are made by drilling holes in the ice and then placing instruments underneath the ice or in it. That’s exactly what we have to do here. We have placed large measuring devices, that require large holes to be drilled, at the periphery of the pack ice ridges and underneath the ice. These are for instance instruments that measure water currents and turbulence. Then we embedded thermistor chains over the whole ridge as well as in the thickest ice, that was more than 8 metres thick in places. With these chains we can observe how the ridges cool, how they freeze in the centre, and how the processes of erosion and disintegration take place on their undersurface.
Commentator: Research in other scientific disciplines is also ongoing. A great deal of weather data is being collected both on the Polarstern and in the Ice Camp. Still lower temperatures than the current low temperature of minus 35 degrees have been measured there and that has led to one or two expedition members experiencing mild frostbite.
Christian Haas: By itself the air temperatures aren’t sufficient to judge how cold it really feels on the ice, because it’s the combination of air temperature and wind strength, what’s called “windchill”, or in other words perceived temperature, that’s important. Unfortunately, some of the coldest periods occurred at the same time as phases when the winds were strongest. Windspeeds went up to 50 km per hour and the perceived temperature fell under minus forty-five, sometimes under minus fifty. This made work on the ice very, very unpleasant and even almost dangerous. Although we have very good extreme weather clothing, a few people still managed to experience mild frostbite on their faces. This is very difficult to avoid when you are really concentrating on your work and you forget how cold your cheeks, or your nose, is getting.
Commentator: The safety of the team is still first priority. In case there should be a medical emergency, that luckily hasn’t happened yet and hopefully won’t in the future, then expedition members can be airlifted out.
Christian Haas: We are approximately 300 kilometres from the North Pole and therefore a long way from any form of human civilisation and from any form of help that we would need if an accident were to occur. Basically, we are further away from help and civilisation than one would be on the international space station. For this reason, we have made contingency plans for how we would obtain help in case it was really needed. One of these plans is that we could be reached by a light aircraft with skis that could land here and bring help or airlift a sick person out. However, such an aircraft would require that we have a more or less even landing strip, which wouldn’t be there naturally, because the ice needs to be thick enough - at least 50 centimetres – for the aircraft to land safely. Because of this, during the last few days we constructed a test landing strip close to the ship, so as to minimise our use of resources. To do this we used Pistenbullys, these are tractors equipped with snow ploughs and rotary hoes [Ed. In English they are also known as “Snowgroomers”]. This Pistenbully prepared a roughly 400-metre-long, 25-metre-wide landing strip, that is very, very flat – so flat that even an aircraft with landing wheels could land here. That was a very important exercise for us to allow us to prepare for the construction a larger landing strip that we will need for the changeover between legs 3 and 4.
Commentator: The scheme for protection from Polar bears is also still active, although so far during leg 2 no polar bears have seen. Instead the camp was visited by other four-legged creatures who unfortunately caused minor problems with various measurements.
Christian Haas: The pin up animal for the arctic is the polar bear and we are prepared for them in all sorts of ways, although they aren’t as dangerous as they are often made out to be. But, to our great disappointment, we haven’t yet seen one. This isn’t perhaps so surprising, because in the middle of winter, when its dark and the ocean is almost completely frozen over, there are neither seals nor any other kind of food. Then the polar bears tend to go South. Therefore, given that our tour of duty was the mid-winter one, perhaps we shouldn’t necessarily have expected to see many of them. But what then did surprise us, although there are past reports of it, is that we were visited by Arctic foxes. Up to 6 of them were seen. They stayed in the neighbourhood of the ship quite a long time, circling the ship and playing. That was something of an occasion here and a bit of a diversion. Naturally, first of all we thought that the foxes were cute animals and nice to look at. However, actually they presented something of a danger to our measurements because they love chewing cables. And accordingly, some of the foxes chewed through some of the cables that we had laid across the ice to connect measuring instruments with dataloggers, batteries or generators, interrupting measurements. But then we were able to successfully protect the cables against the foxes and were able to drive them away and for the last two weeks there haven’t been any more foxes here and our work could continue unhindered.[Ed.: on the MOSAIC webpage on 6 January a further instance of damage was discovered and reported and the remark made that the foxes had been seen at “the end of December”]
Commentator: Christian Haas is looking forward to the coming weeks and the upcoming research work, although the conditions for it won’t be made easier by the continuing polar night and the further decrease in temperatures. He is very focussed on keeping the goal of the MOSAIC expedition in his sights.
Christian Haas: We are still moving into February and March, that’s actually the coldest season in the arctic. That means that weather conditions will become even more extreme. Nonetheless, I believe we will continue to work enthusiastically on the ice. Because now, just as we are slowly beginning to get good time-series measurements of atmospheric conditions and of ice and water conditions, the information is becoming increasingly interesting and we are getting nearer to fulfilling the goal of the MOSAIC expedition to investigate the interaction between the atmosphere, ocean and ice and, and we shouldn’t forget that, the Biology of the arctic. So I hope that we will continue to be able to work unhindered. Naturally one or two ice deformation events should also take place, if possible, at quite a distance from the ship. We will continue to expand the radius of the area that we move in. Apart from that, I hope that we might indeed get a storm that will bring us some snow. Till now the snow has been very sparse, the snow cover is between eight and twenty centimetres. And what we also hope for, even if it may sound paradoxical, is that at some stage we get an intrusion of warm air that will temporarily give rise to very high temperatures and even to a little rain, as has been seen with increasing frequency in past years and about which there has been much speculation as to the effect it has on ice cover and ice growth. We now have a unique opportunity to observe the phenomena on the spot and that is absolutely necessary to better understand these processes.