Week 3

A difference of opinion as scientists search for the perfect ice floe

This past week the ship has battled through patches of thick ice and snow. It can be a frustrating task, and on occasions we have made no more than just a few metres in five or six hours of hard ramming of the ice. On the other hand, when not stuck, it is exhilarating to stand on deck and watch (and hear) the grinding and crunching up of the ice. Ice floes containing many hundreds of tons of ice are moved aside as if they were of no consequence at all.

Polarstern vessel ramming the ice © David N Thomas

Polarstern vessel ramming the ice © David N Thomas

Twenty days into our journey, we thought we had finally arrived at our new home - the ISPOL ice floe (ISPOL is Ice Station POLarstern) - only to be thwarted at the last minute. The oceanographers on board were looking to get as far west as possible into waters only 2500 metres deep. They are investigating the temperature and salinity (a measure of how salty the water is) of different water layers below the ocean surface. Reaching this specific water depth was critical to their investigations. So once we had ticked that off, we could set about looking for a suitable ice floe for the other groups.

Ice experts on board were given the task of selecting an ice floe. Not an easy task since the requirements of the various groups on board are quite different. Some want to deploy heavy sampling devices and weather stations. For them a thick, old floe (more than two metres thick) would be the best. Others want to set up equipment under the ice for which they need to cut large holes out of the ice. Obviously for them a thin floe (about 1 metre thick) would result in considerably less work.

Light playing a lovely trick as the snow turns an intense blue © David N Thomas

Light playing a lovely trick as the snow turns an intense blue © David N Thomas

In short there is not a perfect floe for everyone, and compromise is the order of the day. The floe we selected looked fine in the morning, but when seven people did a three hour survey using snow mobiles and sledges, it was clear that it would not serve our purposes. So to the disappointment of all it was decided to carry on travelling to look for a better floe.

As solid as the ice looks, we always have to remember that it is only a relatively thin skin on the oceans surface that is moved around by the oceans currents and of course the wind. I remember another ice camp I made in 1998, where we were working in a large ice filled fjord. We went to sleep quite content with our day's work, and next morning looked out to find that 12 square kilometres of ice (size of a small village) had disappeared in just 6 hours, and we hadn't heard a thing! The pack ice is surely an unpredictable place, and our future success is at the mercy of the weather over the next few weeks.

Not all ice is clear or white - microorganisms discolour the ice a rich coffee colour © David N Thom

Not all ice is clear or white - microorganisms discolour the ice a rich coffee colour © David N Thomas

Our problems finding a floe is a perfect example of how unpredictable pack ice research can be. It is after all one of the most hostile places on earth. We have battled to our final position, only to find ice conditions and even the weather working against us. Because of bad contrast and visibility we cannot use the helicopters, which is a major handicap, because they are our main tool for surveying large areas in a short time.

Time is running on, and we must set up camp in the next few days, and hopefully the ISPOL floe is just around the corner. In the meantime the American scientists on board are treating us all to a Thanksgiving Day celebration. The cook even had some turkeys in the freezer!

David Thomas
25th November
69°S, 54°W