AWI resumes Arctic measurement flights | Polarjournal
The research aircraft “Polar 6” and “Polar 5” have arrived on Svalbard for the start of the flight campaigns. (Photo: AWI, Esther Horvath)

After a five-month suspension due to corona-forced constraints, the two German polar research aircraft Polar 5 and Polar 6 took off from Svalbard on Sunday, August 30 for their first Arctic measurement campaigns of the year. The scientific measurement flights far into the central Arctic serve the exploration of atmosphere and sea ice and complement the extensive research program of the MOSAiC expedition.

Jakob Belter from the Alfred Wegener Institute works at the Longyearbyen airfield on the “EM Bird”, which is mounted on the research aircraft “Polar 6”. (Photo: AWI, Esther Horvath)

The studies focus on cloud formation over the Arctic Ocean and whether the sea ice studied as part of the MOSAiC expedition was thicker or thinner than in the past two decades and how the above-average summer temperatures affected the Arctic ice sheet.

Originally, the MOSAiC expedition was to run four flight campaigns – two in spring and two in summer. Due to the Corona pandemic, however, the measurement flights had to be cancelled in the spring. The anticipation of the 26 scientists and technicians involved is all the greater now. “We are very relieved that our two summer campaigns can take place despite the Corona pandemic and we thank both the Government of Norway and the Governor of Svalbard for the good cooperation in the run-up to the event. Without their support, a research project of this size would not have been possible under the given conditions,” says atmospheric researcher and campaign manager Dr. Andreas Herber of the AWI.

The research aircraft “Polar 6” and “Polar 5” in Spitsbergen. In the foreground is the “EM Bird” of the “IceBird” campaign, which is mounted on the Polar 6. (Photo: AWI, Esther Horvath)

How do clouds form in the Arctic?

The German research aircraft “Polar 5” and “Polar 6” are the first two foreign aircraft on Spitsbergen since the lockdown. They will take off from Longyearbyen Airport to the central Arctic and spend about four to five hours in the air on each flight. The measurements carried out focus on two key scientific questions. The atmospheric scientists involved want to find out how clouds form over the Arctic Ocean and what role aerosol particles and air vortices play in this. For this purpose, the scientists equipped “Polar 5” with various meteorological measuring instruments such as a light radar, a photometer and several radiometers.

Previous studies have shown that clouds are a major contributor to the rapid warming of the Arctic. Modern atmospheric models, however, have underestimated so far the influence of clouds and do not yet properly simulate it. For this reason, the team of researchers from the Alfred Wegener Institute, the Universities of Leipzig, Bremen and Cologne as well as the German Aerospace Center (DLR) will measure the air masses over the Arctic Ocean on a large scale and examine in detail all factors relevant to cloud formation. It is also planned that the aircraft will follow the route previously taken by the research icebreaker “Polarstern”. In this way, the measurement data collected in the air can complement and complete MOSAiC research on the ship and on sea ice.

Was the MOSAiC ice floe particularly thick or thin?

While “Polar 5” measures the atmosphere, the sea ice physicists on board “Polar 6” concentrate on the sea ice cover of the Arctic Ocean. Their campaign aims to document the thickness and surface properties of sea ice in the Fram Strait and in the central Arctic Ocean. The so-called EM-Bird – an electromagnetic measuring system that is towed over the ice surface by the aircraft at a height of 15 metres is mainly used.

Low-flying of the measuring aircraft “Polar 5” with a towed EM-Bird probe to determine the thickness of the sea ice. (Photo: AWI)

The ice thickness measurements are part of the IceBird long-term data program, in which AWI sea ice physicists have been studying the Arctic sea ice cover twice a year for nearly 20 years – once at the end of winter, when the ice has reached its maximum extent, and once in summer, when it shrinks to its annual minimum. “This summer, we also have the exciting question of whether the state of the sea ice areas studied as part of the MOSAiC expedition somehow stick out compared to our long-term data. In other words, whether the ice was thinner or thicker than in the past; whether the high summer temperatures have afflicted it in a special way or whether a striking number of ice ridges have formed due to its rapid drift,” says AWI sea ice physicist and IceBird campaign manager Dr. Thomas Krumpen.

Source: AWI, Bremerhaven

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