Buoys on ice
By Leonard Rossmann |
On the 27th of December it was time to say good-bye again. Since we left the Neumayer III station, we had four extra scientists on board. Their main goal was the Drescher inlet. There they want to spend the next 5 weeks and run a field campaign until we pick them up again. They are going to equip seals with infrared cameras and sensors to measure depth and salinity. Furthermore, they planned to dive with a remotely operated vehicle (ROV) under the ice in order to study the under ice fauna. Their planned adventure was described in more detail in the previous entry.
Hence, on the 27th we had to unload all the equipment they need. Sometimes it is hard to believe how much logistic and just stuff four persons need to set up a camp in the extreme conditions of the Antarctic. We moved around 11 tonnes of equipment by helicopter. It was terrific to see how a helicopter can carry heavy loads. On photo 1 the helicopter carries a so-called ‘Tomato’, which serves as a kitchen and a safe spot against strong winds on the ice. After a day of unloading and transportation to the field campsite, Polarstern left the spot and continued its journey further south.
During the cruise the vessel already faced strong ice conditions. Sometimes this stops the ship to go at high speed to the next location. In addition, it can prohibit trawls for the biologists and water sampling for the oceanographers on board. Such a situation can push on the mood of the scientists, but there are two souls on board, who celebrate strong sea ice extends. They are the members of the sea ice physics group. They are packed with buoys, which they want to deploy on the sea ice. These autonomous buoys are placed on the sea ice in order to measure ice and snow thickness and its change over the year. They last around two years and measure every day. The data is sent via satellite to Bremerhaven and is freely accessible on the website www.meereisportal.de.
During the journey we will deploy around 25 buoys. There are 3 types of buoys. The first one measures the snow depth via four acoustic sensors. This buoy has a 1.5 m long mast with the four sensors arms reaching out ca. 60 cm. The change of snow height is measured by run time of an acoustic wave, which is reflected by the snow surface. The second buoy is a yellow box with a thermistor string going through the ice into the water. By measuring the temperature and thermal conductivity it is possible to identify the boundaries between ice and ocean, ice and snow and snow and air. This gives information about sea ice growth and snow cover. The third buoy type looks like a giant lolly and simply transmits its coordinates to track the drifting behaviour of the ice floes.
After saying good-bye to the deployed buoys on the ice and lifting off with the helicopter, it is a matter of hope that the buoys will live long and in peace with the sea ice floe. The buoys will follow hopefully a corkscrew curly path through the Weddell Gyre.
On our cruise we had very good deployment conditions up to now and are hopeful that even more buoys can be deployed far south in order to repeat deployments from earlier cruises.
Best wishes from the ice
Leonard Rossmann
