International cooperation for climate research

The kiss of an arctic fish, three months of darkness, crunching ice, a beautiful and awe-inspiring landscape and polar bears in the wild: These are memorable memories that the researchers of the MOSAiC expedition bring back home. Weeks or months away from home on a research icebreaker, this has made the very different people from 20 nations into one big team.

All participants arrived with their own preparations, questions and experiences. Pauline Snoeijs Leijonmalm, Professor in Marine Ecology at the University of Stockholm in Sweden, spent eleven weeks on the "Polarstern" and four weeks on one of the Russian icebreakers, which regularly called at the research vessel for supplies and team changes. She led two research projects - one on fish and one on the metabolism of certain microbes in the ice. "I was amazed at the sounds the ice makes when a ship is frozen," says the Swede, who had previously completed other Arctic expeditions. "It was so loud, so variable and so different from anything I had heard before." The most beautiful moment on board was when she kissed an Arctic fish. "He was actually on the ice - the first fish we caught!"

Valuable information about the Arctic climate system

It was not his first Arctic expedition that Gunnar Spreen has now completed. The head of the section "Remote Sensing of the Polar Region" at the University of Bremen was already on board on the first leg of the MOSAiC expedition and also participated in the last one. The focus of his work was the measurement of the interaction of sea ice with microwave radiation. "This may sound rather abstract," he notes and explains: "But if we understand and model these processes better, we can derive specific information about the sea ice and the Arctic climate system from satellites. For example, about the depth and thickness of snow and ice, which influence the flow of heat from the ocean into the atmosphere". The data collected by him and the other scientists would help to better quantify these changes through satellite observations.

So many days on one ship with very different nationalities - isn't that difficult? "Nationalities are certainly not crucial for interaction with different people. We worked together very well," says Spreen. Challenges for the experienced expedition participant were more likely to be on the ice itself. "We were always aware that it would be difficult to maintain an intact camp for a whole year on the ice, which in the end was much younger, thinner and more dynamic. However, the fact that our camp would be damaged by cracks and ridges, which regularly form even in the middle of winter, took me somewhat by surprise". Measurement strategies had to be adapted and the warehouse structure had to become more flexible. The deformation of the ice was also the most impressive experience for him. "Within a few dozen minutes, ridges formed in front of our eyes, and the sound that ice can make is amazing."