Polarstern at an ice flow on station work. Foto: Alfred-Wegener-Institut /Stefan Hendricks
Focus on the Arctic Climate: German Scientists on Missions in the Arctic by Ship and Plane
Leipzig, 11.05.2017
It is the end of May and time for many Germans to take out their bikes and enjoy the pleasant temperature. However, this is not on the minds of more than 60 meteorologists and physicists. Instead, their thoughts are on their upcoming journey through Arctic regions in frigid temperatures. Soon, they will start their elaborate survey of the regions between Greenland and Spitsbergen (Svalbard) on board two specially equipped research planes and one research vessel. Their mission includes finding out what role the Arctic cloud cover plays in the amplified Arctic climate change. The scientists will have eight weeks to answer this and other questions. Their work will contribute to the project 'Arctic Climate Change' funded by the German Research Foundation (DFG; Deutsche Forschungsgemeinschaft) as part of the Umbrella Research Programme (DFG Sonderforschungsbereich) Transregio 172.
Professor Dr Manfred Wendisch from the University Leipzig masterminds the above named umbrella research programme and summarises: "In recent years, we investigated the specific behaviour of clouds under arctic conditions many times, and we were able to gather important results. However, this time, we will break into a new dimension. We are thrilled to continue our research in the Arctic region on such a large scale." Aside from the University Leipzig, the universities in Bremen and Cologne as well as the Alfred Wegener Institute of the Helmholtz Zentrum für Polar- und Meeresforschung (AWI of the Helmholtz Centre for Arctic and Marine Research) and the Leibniz Institute for Tropospheric Research (TROPOS) in Leipzig (Germany) are part of the research programme.
As Professor Wendisch reports, the observed increase of the apparent surface air temperature in the Arctic exceeds global warming by a factor between two and three. This is how he characterises the drastic consequences of climate change: "This phenomenon is known as polar amplification. It leads to dramatic changes of many climate parameters in the Arctic. For example, satellite data show diminishing summer sea ice coverage of the Arctic Ocean in the last 30 years. 25 years ago, the ice coverage of the Arctic Ocean was twice the current level. In forty or fifty years, there might no longer be any Arctic sea ice."
The objective of the SFB Forschungsverbund (SFB umbrella research organisation) is the long-term observation of the Arctic climate development. This will fine-tune and increase the reliability of prognostic models, which forecast the amplified temperature increase in the Arctic region. The Arctic amplification has a wide array of causes. Some of these causes may not yet be completely known. In the first project phase until 2019, the DFG will provide ten million Euros to reach this objective.
The current survey consists of two missions, which the scientists will set out to accomplish in eight weeks. On the 24th of May, the research vessel 'Polarstern' (Polar Star) will cast off from Bremerhaven. TROPOS Director Professor Dr Andreas Macke will lead Mission 'PASCAL'. For ten years now, Professor Macke performed regular atmospheric measurements in the North and South Atlantic. Now, for the first time, he will perform measurements in the Arctic ice. Just like the two planes 'Polar 5' and 'Polar 6', the Alfred Wegener Institute (AWI) also operates the 'Polarstern'. The two planes will lift off from Longyearyen (Spitsbergen) for their first research flights on the 22nd of May. Their 'ACLOUD' Mission will proceed under the auspices of Manfred Wendisch and André Ehrlich of the University Leipzig.
Manfred Wendisch and his crew of dedicated scientists focus on the role clouds play in the amplified Arctic climate changes. He gives us a run-down on the missions: "Both the airplanes will be in the air for a total of about 80 hours. We will use remote sensing methods to study the clouds from above and below. In addition, we will take direct samples of the clouds. In particular, we will measure the number and size of cloud droplets and ice crystals as well as the cloud content of ice and liquid water. The data obtained using coordinated measuring flights will complement each other." The scientists eagerly await data showing the relationships between clouds and the sea or ice surface: "The data will reveal turbulent heat and moisture movements as well as solar and terrestrial flows of radiation energy, snow and rain precipitation, the characteristics of aerosol and cloud particles as well as trace gas concentrations."
The scientists will coordinate the data measured from the air with observations made on the ground. Furthermore, the crew of the research vessel 'Polarstern' will build and operate a 'drift station' on the sea ice. This station will move with the sea ice. Andreas Macke elaborates: "We will gather detailed data on the interdependencies between clouds, aerosols and sea ice, which will also be an important reference for the measurements obtained on board the planes. This is also important for the spatial comparability of data." All in all, the measurements will cover an area of about 20 square kilometres and make use of lidar, radar, tethered balloons, drones and observational networks to measure radiation. Andreas Macke adds: "The collaboration with scientists on the Polarstern Expedition working on oceanographic, geophysical and biological projects is also very interesting because their input helps us to understand the Arctic in all its complexity."
The group around Professor Dr Justus Notholt from the University Bremen measures the composition and size distribution of clouds. Parallel measurements in the infrared spectrum made on board the Polarstern will provide data on the composition of the atmosphere. Professor Dr Susanne Crewell and the scientists from the Universität zu Köln (University of Cologne) around her expect novel insights into the cloud structure and the roles of clouds in Arctic warming.
The DFG funded the large equipment called MiRAC, which made these insights possible. The MiRAC device allows measurements based on a combination of active (radar) and passive remote sensing (radiometry). What is the significance of these clouds for the Arctic? Do the observed clouds exist all year, and are they of the same type all year long? Do the clouds change by composition and type in the course of a year and are there long-term trends? How do the cloud data explain the temperature increase in the Arctic?
The German/French research station AWIPEV in Ny-Ålesund on Spitsbergen with its diverse arsenal of measuring devices offers excellent opportunities for the long-term observation of the Arctic climate. The scientists from the University of Cologne decided to bring the sister radar device of MiRAC to the research station. This gave them the opportunity to survey the inner structure of clouds with a height resolution of only a few metres. Professor Crewell explains: "We want to use the equipment to find out whether thin layers of liquid water in clouds can act as insulating layers."
The 'Polarstern' Expedition will end on the 20th of July in Tromsø (Norway). For almost two months, the expedition will provide data covering the beginning of the Arctic melting period. The last members of the ACLOUD survey mission will return to Germany earlier on the 28th of June. Plans for more measurements in 2018 and 2019 already exist. They include measurements from airplanes taking off from Greenland.
Further information:
Prof. Dr. Manfred Wendisch
Leipzig Institute for Meteorology (LIM), „ACLOUD“-Mission
Telefon: +49 341 97-32851
e-mail: m.wendisch@uni-leipzig.de | Internet
Prof. Dr. Andreas Macke
Leibniz Institute for Tropospheric Research (TROPOS), „PASCAL“-Mission
Telefon: +49 341 2717-7060
E-Mail: macke@tropos.de | www.tropos.de
Follow the expeditions e.g. via "Polarstern"-Blog as well as using twitter-hashtag #arktis17.