11 January - 16 January 2008

Hurray, we accomplished our logistic task. Polarstern created a nice docking place for Naja Arctica after 8 days of long battle against the ice. Here is the story that looked long time as tragedy but ended as success. It all begins with ice.
Sea-ice, shelf-ice, fast-ice, even for dessert – ICE! Polarstern was surrounded by ice. For over a week Polarstern has been struggling to free a pier for Naja Arctica to unload equipment for the construction of the new Neumayer III Antarctic station. This situation was tense, for at least two reasons. The three programmes of the International Polar Year currently on board Polarstern have not fulfilled half of their duty; in fact one programme has not even started. And in about a month the short Antarctic summer will have passed its culmination leaving limited time for assembling Neumayer III. After a brief autumn the long winter will take hold of the continent. Time is flying and the weather is the determining factor. Let me explain all this in more detail.

All this started in mid December when Polarstern had reached the edge of the winter sea-ice zone at the northern rim of the Weddell Gyre. In winter, an area in the Antarctic Ocean equal to the size of the United States of America freezes over. Normally by mid summer (i.e., January) only marginal remains of sea ice are left at the boundary to the continent, where it meets the shelf-ice. In contrast to only 1 to 2 m thick sea-ice formed from freezing seawater, the shelf-ice originates from the up to 4000 m thick ice masses on the central Antarctic continent with an age of hundreds of thousands of years. Slowly sliding toward the sea, the ice glaciers thin down considerably to a few hundreds of meter thickness when they enter the ocean over the continental shelf. First this shelf ice floats but finally breaks off forming the huge (male) icebergs that either drift with the wind and currents or get stranded on shallower parts of the continental shelf.

Polarstern found her way to Neumayer shortly before Christmas and supplied Neumayer II station as reported earlier. Also Naja Arctica following Polarstern’s route through the sea-ice area docked in Polarstern´s port in the fast-ice in Atka Bay on 18 December. Fast-ice basically originates from sea-ice but is firmly attached to stable structures like rocky coasts, islands or as in our case the shelf ice of the Atka Bay. When floating sea-ice is pushed against the stable fast-ice by storms and currents, it piles up forming massive barriers of tiled, compiled and solidly refrozen ridges that can reach heights of more than 5 m above the water with keel depths of more than 15 m. That in fact was the situation we were facing in December 2007 along Atka Bay at locations where the height of the shelf-ice edge did not exceed 12 meters; i.e., where it was reachable for Naja Artica´s cranes to unload the equipment for Neumayer III, with up to 40 tonnes being too heavy to be transported over the sea-ice.

Intense search by helicopter flights and proper evaluation of the situation by Polarstern´s captain, the chief scientist, the captain and officers of Naja Arctica, members from Neumayer II station and the construction company concluded on Dec 20, that the ice situation was too stable to start any sensible breaking and/or unloading operations. In addition, 100% sea-ice coverage prevented any large manoeuvring possibilities for Polarstern. Bad news for the construction team, as the first deadlines of the ambitious plans to complete the outer station structure during the summer campaign 2007/8 already had passed. Thus Polarstern was temporally freed on at-call mode to perform scientific work in the Lazarev Sea, intended to contribute to three leading German projects for the International Polar Year, as explained in detail in previous reports. This research time ended abruptly as the call came soon when the sea-ice was gone and the coastal polynia opened. By 7 Jan. Polarstern was back starting to break a channel into the 1.5-mile wide fast-ice facing the northern shelf-ice docking place.

Ramming continued day and night. Fast was the first progress in ploughing inwards, than came a ridge, 200 m wide up to 8 m deep. More than 100 cm of snow on top the ice stopped Polarstern bullying attempts by absorbing all kinetic energy with its soft, white cushion. Stuck again, firmly glued by adhesive snow to the upfolding underground. Full power backwards, trimming changed by pumping water into the aft ballast tanks. Next try, only some meters gained. The channel on purpose was made 200 m wide to allow the broken conglomerate of snow and ice to slowly drift backwards out into open water. The negative record was the extension of the channel inwards by only 90 m within one entire day.

The long awaited storm approached. Up to 9 Beaufort easterly winds promised help in breaking the massive ice plains. Meanwhile Polarstern escaped the channel to avoid being trapped by merging sea-ice – everything is possible down here. But what a shock after two and a half days blizzard: nearly nothing had changed in the fast-ice; instead all the sea-ice from the east now had concentrated around Atka Bay, as satellite photos showed clear open polynia waters east and west of us. And the weather became stable again. Back into the channel, lets break again, mission still not achieved. The scientists on board understood, but did not deeply love the idea of spending many more days on logistics, losing time for science.

What can still scientifically be accomplished in the remaining time? To set priorities we compared collected data and drew first conclusions. Important information (from oceanography and krill) in the southeast corner is already missing. One IPY project has not even started. It is the synoptic view on water mass properties and ocean currents and their relation with ocean productivity all around Antarctica that depends on Polarstern´s contribution from the South-East Atlantic sector of the Southern Ocean. Maybe the international community will have to face a gap, Germanys contribution missing, and thus will not be able to identify the processes that determine the regional differences in the uptake of energy and carbon (CO2-drawdown) in the Antarctic Circumpolar Current, which would be of fundamental relevance to better assess the Southern Ocean’s role in the global climate system. So what can still be achieved? We will only know, once done with the ice.

Southeasterly, later southwesterly winds open the polynia in front of the fast-ice again, but remain too weak to affect fast-ice movements. Polarstern widens the channel by breaking big chunks of fast-ice flows and pushing them to sea. The idea is to make space for Polarstern to ram further towards the shelf ice and to create space for Naja Arctica later to manoeuvre in the channel in order to find a suitable docking place to finally start unloading.

On Monday we visited the Neumayer station and met with the construction team again, exchanging plans and ideas. Both sides of this operation were contemplated (the construction aspects on land and the science issues on board ship). Univocal consensus was confirmed. Polarstern does all she can to achieve the logistic goals and Neumayer realises the pain of the scientists and the consequences for their programmes on board.

And on we go. The captain follows his new strategy in widening the channel first so that she can fulfil a full turn in medium speed. Than very gently moving out the broken flows by using a tiny bit of Polarstern´s 20.000 horse power to touchy push the flows outside into the open polynia. Water is her element and once freed from ice, the sickle bow of the circling ship cuts slide after slide off the stubborn ridge. Like a big turning knife the ship erases what had been once the barrier to success. On 16 Jan. at 02:20 in the morning about 400 m shelf-ice line was freed and ready as perfect parking slot for Naja Arctica and her long awaited loads.

And now – some did not believe it even when we started – were are steaming to the first station on the Greenwich meridian, on which we will perform the very much reduced science programme for the remaining 14 days of working.

In July 2006 I had a winter cruise down here and it went fine with minus 35°C, and this summer at minus 1°C and with the logistic duties given the ice is a real pain…
Not giving up hope to succeed, a clever strategy and long-lasting work was the key to success.

Uli Bathmann and 52 other eagerly waiting scientists