The New Year started immediately with comprehensive station work. Occasionally, however, you could get the impression that Neptune was unhappy with this work being carried out in his private home.
He refused giving sample material to the gear that intended to recover seafloor surface sediments, sent back to the surface the small submarine (Remotely Operated Vehicle – ROV) after a difficult mission with all its thrusters blowing and glowing, and, after the deployment of the fish trap, triggered a discussion on board whether the name for this gear is justified...
And then the first weekend in 2016 arrived. You notice that it is Saturday only because tasty stew with fresh bread is served for lunch (probably we have the best baker on board within thousands of square miles). Well fed we are able to work systematically and with endurance. We complete an oceanographic transect along 75° South, thereby crossing the oceanographically and geologically important Filchner Trough and ending up on the shallow shelf North of A23A. Because of 9/10th of sea-ice coverage it takes us six full days to complete the 75°S profile, which is only 200 km long (direct line) but requires several sea ice related detours. Indeed, ice with a thickness of 1-2 metres and additional half a metre of snow cover can stop “Polarstern” in her tracks for a while because it simply ignores the power of our ship’s propulsion with 20,000 horse powers. The ship’s “Intering” system, however, is able to shake it off, and in difficult situations the crane assists (apologies that only an insider will understand this but a detailed explanation would be lengthy and require usage of very technical terms).
Where and when is a better place and time for discussing whether the recent El Niño event influences Antarctic sea-ice extent than breakfast, where you have your muesli surrounded by huge ice floes? The thick snow cover, however, delays our progress. The use of all four engines would result in faster drainage of our fuel tanks, which would counteract our further plans: Ronne Depot is far ahead. Just South of A23A we will have to make a definite decision (A23A? See next weekly letter; only this hint for the moment: A23A is not a German Autobahn).
Don’t get the impression that we only roughly estimate the sea-ice coverage of the Southern Ocean: Ask our sea-ice physicist on board who is in charge of an entire observer team (you remember the “ice ruler”?) and then you get all the details:
The precise average sea ice and snow thicknesses on the way from Halley to the end of the 75°S profile are as follows:
First-year sea ice =81 cm, snow =28 cm. Multi-year sea ice =153 cm, snow =66cm. All types of ice (including “brash ice” which smashed itself): ice =95 cm, snow =44cm.
Are these enough details? A few “precise” scientific data can also be published in a weekly letter.
Even today polar research is a daily challenge that we (mostly) master successfully: The complex processes and operations on board of “Polarstern” when she is full in action can hardly be summarized in a weekly letter: The working deck is packed with gear, which sometimes is deployed with the sliding beam over the side and sometimes via the A-frame astern. On the working deck geologists sample their box corer while oceanographers are preparing one of their drifters nearby. Further astern biologists recover their fifth successful multiple corer in a row, and above them a helicopter takes off to study the sea ice cover from the air and in more detail. Meteorological observatory and echo sounder room are staffed permanently and the turbulence laser emits its beam above all this. What an achievement for a single ship – and this already for 33 years at sea!
The 14 CTD casts along the previously mentioned 75°S transect do not only give evidence that the sea water there is cold but also provide plenty of liquid sample material for all “hydrophilic” disciplines on board. The various nets provide material for all the biological working groups and water-proof cameras (OFOS) deliver a photo collage and video footage of the seabed. The gravity corer is toppled over by Neptune but several other corers and grabs manage to fetch “cut outs” from the seafloor on deck – be sure that hardly anything left from ¼ m3 of sediment is returned to the ocean. Afterwards, however, we have to get rid of the sticky mud and clean the deck as once did the sailors of the “Flying P-Liners“ before us (in some aspects our ship continues the historical series of ship names of the shipping company Laeisz: Padua, Passat, Pamir ... Polarstern – only “flying” doesn’t work for us at the moment).
We also have colleagues on board who can/must leave the ship occasionally via helicopter in order to explore in more detail this astonishing white desert which slows us down: The sea ice physicists. An eye witness describes their field work activities accurately as “buoy planting”. We highly recommend reading the “Polarstern” blog as a supplement to this weekly letter. There, you will find out more about the buoys, their mission and the drift of sea-ice rafts (these days also weekly letters need to refer to “Supplementary Online Materials”).
We read in the news: Germany’s motorists suffer from black ice appearing within minutes - the oldest ice in Antarctica is roughly 1 million years old. And: There is 3 mm of snow in Bremerhaven - here, there is 3 km of snow and ice just around the corner.
Our planet really offers a huge variety!
Scientists and crew send best wishes from the far South
