Between Ile-de-France and Norske Oer

On Monday we therefore continued our voyage toward the south. It is a consolation to know that these moorings may be safely recoverable in one or two years from now and will also continue to record measurements.

Thereafter we spent the entire week at a close distance from a chain of islands located directly in front of the coast of Greenland between Norske Oer in the north and Ile-de-France in the south. At times when the fog receded we could catch sight of winterly, rocky coastlines and one or the other polar bear. In partly difficult sea ice conditions we successfully carried out hydrographic measurements along four different sections. The scientific goal of the oceanographers were to study the circulation pathways of the Atlantic Water both along the axis of Norske Trough and between the trough and Jøkelbugten, an embayment located to the west of the aforementioned island chain. It is in this bay that the Zachariae Glacier discharges the ice masses supplied by the Northeast Greenland Ice Stream – the same ice stream drained from by the neighboring 79°N Glacier.

The water depths around the island chain are still largely unknown today. Owing to the navigational skills of the bridge personnel aboard Polarstern, the geologists conducted a survey of the bathymetry using the vessel mounted swath echo sounder – among impressing wide and huge icebergs. After the surveys, the oceanographers conducted hydrographic measurements at positions based on the freshly produced depth charts. The data will allow us to understand, in which way the Zachariae Glacier is exposed to the inflow of Atlantic Water. This work in turn was accompanied by a highly successful geology programme relying on gravity coring.

In addition, the benthic biologists operated the multicorer at 3 selected sites and further can look back on a deployment of their lander system and its subsequent recovery two days later. Fine progress can also be reported from the sea ice biology team. Their quadcopter – designed to collect air samples to establish the distribution of methane in the air column – accomplished a flight up to a height of 1000 m.

Meanwhile the poor visibility caused by clouds, fog and also icy rain restricted the helicopter based work substantially. Flights over larger distances could not be conducted at all due to security reasons. Despite of the adverse conditions, the helicopter pilots managed to make use of short weather windows, such that the geodesists were able to both install a GPS measurement station on an island near-by and subsequently recover it later in the week. At the same location the geologists succeeded in collecting cosmogenic rock samples. Further the oceanographers succeeded in conducting a depth sounding and hydrographic measurements from an ice floe using mobile instrumentation in Jøkelbugten, which is out of reach of Polarstern due to the mélange of fast ice and icebergs found in the bay. Other important aims depending on helicopter flights, however, like the installation of an ice buoy right next to the Zachariae Glacier or additional glaciological measurements had to be cancelled, unfortunately.

In contrast to the beginning of the week, the subsequent mooring work went absolutely smoothly. Within just one day we were able to recover all four moorings on the Ile-de-France section across Norske Trough that had been deployed one year ago. The data will provide us with important information on the strength and fluctuations of the Atlantic Water circulation in Norske Trough.

Finally, we celebrated our mid-cruise barbecue party this week close the southern tip of Norske Oer.  Two charcoal barbecue sets were placed in a wind-protected area on the working deck, and a tasty variety of meats, salads and many delicious things more had been prepared for us. Our deepest thanks goes to the kitchen, service and deck personnel on board, who made this wonderful evening possible for us.

Many greetings on behalf of the entire scientific crew on board,

Torsten Kanzow