27 July to 2 August 2008

Research in the polynya and search for the seismic stations

On July 27th we interrupted our research in the Northeast Water Polynya to complete the 78°50’ N transect and to recover the seismic instruments from the ice floes. The days showed us how rapid the weather can change in this region: it was often foggy but in between also sunny with a good visibility.

From July 14th on, we have been heading towards the sea ice in helicopters to deploy one or two seismometers on ice floes above the Lena Trough, which is situated centrally between Greenland and Spitsbergen. The deployment must be often done during times of fog patches, and therefore our search for the best possible location was limited. The instruments were positioned on the flanks of pressure ridges. These are parts of ice floes where two floes had grown together, while they were pressed against each other. There a seismometer was dug into and covered by snow. A red box and a red flag were raised to save the equipment from the weather and ease recovery.

However, this turned out to be the literal search for the needle in a haystack although a sender transmitted the position of the station 24 hours a day, which we got via e-mail to the ship. During the course of the day we managed to recover 8 of the 9 stations, which took us, the two helicopter pilots and three seismologists, 13 hours. But the ninth station was still missing. It had not transmitted anything since lunch time. Being outside the range of the internet we could not receive the position directly. Finally, the search was successful on July 29th. Despite a short distance of 30 miles from the ship, it still took 3 hours and a satellite telephone connection to get the position, to locate the station in the fog. Now the data will be read out from the instruments and some preliminary interpretation can be done.

During the night of July 30th we were steaming to the North to begin measurements along the next transect above the continental slope towards the Greenland coast at 79°50’ N. The western part of this region belongs again to the Northeast Water Polynya. There are a lot of huge icebergs of a size of 300 x 300 m, which resemble icebergs found in Antarctica. Due to their size they are grounded on the shallow areas in the polynya. They originate probably from the Nioghalvfjerdsbrae, the 79°-Glacier. We speculate that these icebergs may be the reason that the ice cannot move out of the polynya region. We tried to break into this ice-covered area but because of pressure ridges along the ice border we had to stop our efforts. Therefore we continued our work in the ice-free part of the polynya, but there were also some large ice floes, and we need a lot of time and power to proceed with our work.

On August 1st in the morning at about 9:30 we could observe a total sun eclipse, which could be only seen in the Arctic. Everybody was outside to follow the spectacle with black glasses. We are now working on our northernmost transect at a position north of 82 degrees. Thereafter we will finish our studies in the Northeast Water Polynya and recover the geodetic instruments, which we had deployed on Greenland.

We the best wishes from the beautiful Greenland coast,

Gerhard Kattner