During this week we moved westward in order to get geological cores at the Sverdrup Bank. Reaching our target area turned out to be again quite difficult due to strong ice conditions and we were thus not able to reach the western part of the plateau.
However, using bathymetric surveys, we were able to find suitable coring sites and took two gravity cores on the slopes of the bank. We also used the second coring side for a last biogeochemical sampling station. Thereafter we stopped the winch related deployment of instruments and headed with a straight course to the edge of the marginal ice zone, since changing wind directions from the south already started to move large ice floes together and we did not want to get trapped just prior to the end of our research expedition. In order to round up the geological program on this expedition we carried out a bathymetric survey at the edge of the marginal ice zone. In this region we encountered only small remains of the ice pieces (Fig. 1), which before were blocking our progress several times during this voyage. The immediate connection between ice-free conditions and proper survey is clearly visible in the cruise track (Fig. 2)
While the bathymetric group worked in shifts for 24 hours, all other scientist got busy with cleaning and packing their equipment back into the boxes. Seemingly endless pack and freight-lists needed to be written and the dangerous goods also needed some paper and attention, before they could properly be stored away. Additional all samples, stored in the various freezers and containers at 0°C, 4°C, -20°C and -80°C needed a proper packing list. Most of the sample will come back with Polarstern in October, when after three other expeditions the ship will finish its Arctic season for this year. After all lists had been completed, the boxes were brought to the working deck and handed to the cargo officer and from there the crew took over to store all equipment safely in various containers of the ship. The packing was followed by a proper cleaning of all laboratories and containers in order to leave a “clean” ship for the next expedition. On Saturday we took course with direction towards Svalbard (Fig. 3). The expedition ended for all scientists (Fig. 4) with a zodiac trip to the shore.
The end of a voyage is a good time to make a resume and thus captain came up with some interesting numbers during our farewell reception of the cruise. In total we spent 39 days and 18 hours at sea, and travelled 6788 km. We performed 68 stations and deployed in total 242 instruments. In order to deploy the instruments 120.707m of cable have been moved on the down- and up-ward operations. We spend 333 hours at our ice stations and the CTD was 58 hours in the water. The overall time of zodiac mission amounted to one day and all nets together spend two entire days in the water.
Despite the unforthcoming environmental conditions we encountered during our TRANSSIZ expedition (Abb. 5; Transitions in the Arctic Seasonal Sea Ice Zone), overall the cruise need to be considered as very successful, since we were able to conduct ecological and biogeochemical early spring process studies from the shelf to the basin in order to link past and present sea ice transitions in the Arctic Ocean. The geological investigations will help us to improve predictions of the potential annual primary production in a future ice-free Arctic Ocean, as well as improving reconstructions of productivity, sea ice and ocean circulation across the last 1-2 last glacial cycles.
On behalf of all cruise participants (Fig. 6) I like to thank the captain and his crew of the research vessel Polarstern, as well as the Helicopter and meteorology teams for the excellent support during our work at sea, and the friendly cooperation during the expedition TRANSSIZ (ARK29-1/PS92).
With kind regards
Ilka Peeken
