Polarstern returns to Bremerhaven

19th Arctic research expedition successfully concluded
On 13th October, Polarstern, research ice-breaker of the Alfred Wegener Institute for Polar and Marine Research, will return to Bremerhaven after a 20 week long research cruise in Arctic waters. Over 200 scientists from 11 nations made use of the 118 metre long ship to research biological, geological and oceanographic processes west of Ireland, in the Arctic deep sea and in the fjords of east Greenland, during two cruise legs.

Into the deep with Victor 6000
Polarstern left Bremerhaven on 22nd May, on course for the French port of Brest to collect the unmanned deep sea vehicle Victor 6000, which belongs to the marine research institute Ifremer (Institut francais de recherche pour l'exploitation de la mer). Victor 6000 is a 4 tonne, unmanned robotic diving vehicle operating down to 600 metres below the sea surface. It is directed with the assistance of several remotely controlled cameras, and can retrieve samples of water, sediment or living organisms as well as sounding the sea-floor, using two grab-arms and various measurement devices. Victor 6000 was used to examine the development of deep sea corals west of Ireland and the Hakon Mosby mud volcano in the Arctic deep sea, as well as monitoring a long-term observation site in 2600 metres water depth. The deep sea expedition ended at Tromso on 7th August, and Victor 6000 was unloaded.

Franco-German co-operation
The use of the French Victor 6000 on the German ship Polarstern is an excellent example of international scientific co-operation. Since the signing of a memorandum of understanding between AWI and Ifremer, the Bremerhaven-based institute has continued a successful record of collaboration with France. In May 2003, a co-operation agreement between AWI and the IPEV (Institut Polaire Francais Paul Emile Victor) was signed, and the merging of the German and French Arctic stations in Ny Alesund, Svalbard into a joint Franco-German station announced. From 14th to 20th October 2003 the Fete de la Science - a large-scale event for the public presentation of science - will take place in France. AWI and Ifremer will present the joint deep sea expedition at the invitation of the French minister for science.

Polarstern in the fjords of east Greenland
On 10th August, 45 scientists hailing from Germany, Denmark, France, Holland and Sweden sailed out of Tromso under AWI leadership for another section of Polarstern's Arctic expedition. Geological, physical, biological and oceanographic research along the coast and on islands of east Greenland featured on the program. The focal point of the first half of the Greenland leg comprised seismic exploration of the continental shelf of east Greenland, with the aim of measuring the magnitude of volcanic activity during the separation of Greenland and Norway around 55 million years ago. Sonic booms (pulses) generated on Polarstern and special accoustic receivers (ocean floor seismograph) installed on the sea bed as well as on the Greenland mainland were used to probe sections of the earth's crust, which is up to 30 kilometres thick.

From Polarstern to the island
During the expedition, led by Dr Wilfried Jokat (AWI) in the north polar seas, scientists did not work exclusively on the water. A group of geologists from the University of Leipzig und the AWI's research centre at Potsdam were carried, together with their equipment, by Polarstern's helicopter to the island of Store Koldeway off eastern Greenland for a three week period. On the island, the geologists sampled several small freshwater lakes, the bottom sediments of which may yield information about the extent of the Greenland ice-sheet during the last ice age. Biologists took water samples from the lakes to examine the structure and function of the microbial food chain in these habitats.

Oceanography in the Fram Strait
The final leg of the Arctic cruise consisted of oceanographic work in the Fram Strait. This region between Svalbard and north Greenland is, at depths of up to 2600 metres, the only deep water canal between the north polar seas and the European North Atlantic. Warm, salty water from the south is carried by a branch of the Gulf Stream through this strait into the north polar seas, influencing the water characteristics there. A shift in these ocean currents could be responsible for rising temperatures, such as were observed last year, in the north polar seas. To test this, AWI oceanographers have maintained a series of autonomous measuring devices anchored to the sea bed across the Fram Strait since 1997. These devices measure continually and must be collected and replaced every year.

The research ship Polarstern returns toBremerhaven on 13th October in the early morning, and will be prepared for her next expedition to the Antarctic, which will begin on 22nd October.

Bremerhaven, 8.10.03