ARK XXIII/2, Weekly Report No. 5

2 to 10 August 2008

The northernmost position and the final geodetic work

During our last week we focused the work on the Northeast Water Polynya region. The ice charts have shown a wide ice-free area north of Greenland. Thus, we used this opportunity to continue our oceanographic and chemical research above the continental slope of Greenland as far north as possible. Our northernmost position was 82°24’. We were often using the ice charts to optimise the regions of our research, so that we don’t need to break through the ice. We were able to do additional work in the polynya, but it was not possible to break into the ice-covered areas although some leads occurred now in the huge ice field.

One of our major interests was to look for water masses of Pacific origin, which were generally observed along the Greenland coast until 2004. Pacific water flows into the Arctic Ocean through Bering Strait, travels along the Canadian coast and exits the Arctic Ocean through the Canadian Archipelago and in former years also along the East Greenland coast. Preliminary calculations show that there might be a small increase in water of Pacific origin but not at all comparable to that before 2004.

During the entire cruise birds and mammals were observed and counted. High numbers of birds were found in the frontal zone of the Atlantic and polar waters probably due to a high accumulation of zooplankton. At many stations zooplankton was recorded with a newly developed system producing excellent photos of the individual species. In total 25 polar bears were counted so that everybody has seen a polar bear during the cruise.

On August 6th, we finished our station work of CTD measurements and water sampling because we had to start travelling back towards Reykjavik. This morning we had a visit by Neptune to celebrate the polar baptism, and he welcomes the newly baptised folks in his kingdom.

The final scientific work was the recovery of the GPS stations, which were deployed from July 24th to 26th. The geodesists from Dresden set up in total 17 GPS stations, seven already during the first leg. At 16 stations stable markers were fixed to the rock, which serve to mount the antenna and enable an identical configuration when repeating the measurements. Station 17 was deployed at the 79-Degree-Glacier to determine the flow velocity of the glacier as well as its vertical motion caused by the ocean tides. The data recorded at the bedrock stations allow a first precise calculation of the station coordinates. By repetition of the measurements it is possible to infer vertical deformations of the Earth’s crust, which are expected to be induced by the postglacial adjustment. All stations were successfully recollected from August 5th to 8th. Seven helicopter flights were necessary, all without any problems due to the great work of the pilots, helicopter technicians and the colleagues of the ship’s weather station. Also the weather was good, thus offering a nice view on the overwhelming nature of Greenland.

All scientific work was a great success. This was only possible because of the professional support and never ending help of captain and crew of Polarstern. Thank you very much!

We are now steaming back to Reykjavik. The last ice floes have disappeared, and we send our best wishes once more home,

Gerhard Kattner.