ANT-XXIV/3, Weekly Report No. 1

Sunday, 17 February 2008

 
The first week since departing Cape Town has passed by and we have left the Subtropics and reached the Subantarctic Zone.
 
The call to port in Cape Town was dominated by a visit of the German Federal Minister of Education and Research, Dr. Annette Schavan. She came onboard with South African Ministerial colleagues, dignitaries and scientists in addition to a group of our colleagues from the French research vessel MARION DUFRESNE. During the visit talks were held along with a workshop and a reception. The event was carefully prepared and the good mood of the 150 guests proved it as a success. The gusty winds which rattled the tent assembled on the helicopter deck for the reception provided a type of foretaste of the events to come during the following days.

Wind prevented the ship which carried the container for the CO₂ programme to call to port in Cape Town for unloading. We decided to wait for this container since it was vital to investigate the role of the Southern Ocean as sink or source for anthropogenic CO₂, which is one of the prominent questions we want to address. Then, the Container Ship was diverted to Port Elizabeth and the container was finally loaded onto POLARSTERN on Sunday night. We immediately prepared to depart and our journey could finally start with three and a half days of delay.

However, we have to admit that the delay had some advantages as well. First, it permitted one of our Dutch colleagues, who had fallen seriously ill, to recover and join us for the cruise. Second, it provided additional time to move the huge amount of material which was unloaded from the containers and was jamming up the decks and passages with the risk of blocking all further progress. If these moves would have been completed at sea whilst the ship was moving it would not have been feasible to become operational so fast. But under the stable conditions of a ship in port, piece by piece the equipment was carried and stowed in the labs, unpacked, built up and put into service. Slowly but steadily the chaos was controlled and the enormous piles of boxes and gear were converted into operational high tech labs. Then we only needed the water from the ocean from which we want to measure in the next 9 weeks a variety of trace substances. These compounds and elements control biogeochemical processes and serve as tracers for the cycling of matter in the Southern Ocean allowing us to better understand its role in the global climate system.  

Cape Town disappeared beyond the horizon and the bright sunshine combined with gusty winds gave way to calm but rainy weather.  The installation of the labs came to an end. Observations started with instruments which are applied from the moving ship with the acoustic profiling current meter (ADCP) and the thermosalinograph among the first to provide data. Then, pumps started to inject seawater from a snorkel in the keel of the ship into the pipes to the labs for analysis and for those who need particularly clean water a fish was used to pump seawater from a certain distance onto the ship.
 
The first stop was dedicated to recover a PIES (Pressure inverted echosounder) which recorded variations in the sea level elevation moored on the sea floor.  It was the first one of a set of those instruments to be recovered and moored again. Then, a test station for the ultra-clean CTD followed. It was brought onboard by a group from the Netherlands Institute of Sea Research (NIOZ). It is supposed to take samples which enable scientists to measure the concentration of dissolved iron in the water.  It is understood that it is highly challenging to measure iron in very faint concentrations on a ship which is mainly made out of iron and after 25 years of service, in spite of the careful treatment by the crew, displays one or other rusty patches. To avoid interference with the ship the NIOZ group had built a special sampling system from titanium lowered with a Kevlar wire which avoids any iron parts in the vicinity of the sampling process. To meet this requirement a monster was installed which fills up large parts of the deck consisting of a huge winch, a power station and a clean room container. The clean water sampler was successfully used during the last cruise of POLARSTERN to the Arctic Ocean but modifications carried out since then required tests again. The tests were successful and proved that the system was mechanically and electronically fully operational.  

On Monday evening we crossed the course of the Norwegian research vessel G.O. SARS, which was on its way back to Cape Town from a cruise on which two German colleagues participated. In spite of having a common programme with moored instruments in the Southern Ocean, we had to restrict ourselves to waving the arms, blowing the horns and a subsequent email exchange of slides taken of each of us, since we could not afford to loose further time on our way to the South.

The next test station aimed on the main work horse of the physical oceanographers, the CTD with the rosette water sampler. Here, as well, the test was performed successfully and water samples and data could be used for the programme. Routine took over fast, but the weather slowed us down when a low pressure system passed nearby providing us with winds of up to 10 Bft. But even though we have been slowed down on our way to the South we are making remarkable progress and busy work is going on in the labs to cope with the water masses brought onboard with our sampling systems.

In this northern part of our operation area station work and steaming alternate with a distance of almost 200 km, weather and sea permitting. Since the focus of our work is south of the Polar Front the distance between the stations will decrease to about 50 km after we have passed this point. However, the gaps in the North will be closed via cooperation with the scientists on the French research vessel MARION DUFRESNE whose focus is on the northern region. Our cooperation in the context of the International Polar Year 2007/2008 will result in a comprehensive survey of the sea area between South Africa and Antarctica.

With my best regard from all onboard

Eberhard Fahrbach