Plattform Platform	Reise-Nr. Cruise-No.	Zeitraum Period	Projekt Project	Arbeitsgebiet Working area
Polarstern	PS106 ARK-XXXI/1.1	23.05.2017 - 21.06.2017	AC? ARCTIC AMPLIFICATION	Arctic Ocean

Fahrtleiter Chief Scientist	Institut Institute	Auslaufhafen Port of departure	Einlaufhafen Port of return	Stationskarte Station map	Schiffsroute Trackchart
Macke Andreas	Leibniz-Instituts fur Tropospharenforschung e.V. (IfT)	Bremerhaven	Longyearbyen

Ziel der Reise / Objectives of Cruise:

The Polar Regions are important components in the global climate system. The widespread surface snow and ice cover in Polar Regions strongly impacts the surface energy budget, which is tightly coupled to global atmospheric and oceanic circulations. Here, the interaction of different Arctic feedback mechanisms is not yet completely understood. For example, the coupling of sea ice, clouds and aerosol in the transition zone between open ocean and sea ice is not fully understood so far. Therefore, this issue has been addressed in the PASCAL (Physical feedbacks of Arctic PBL, Seaice, Cloud And Aerosol; PS 106.1) project to improve our understanding of the recent dramatic reduction in Arctic sea-ice in the boreal summer. For this purpose the TROPOS-OCEANET and aerosol instrumentation on board of POLARSTERN provide standard and additional spectral radiation measurements to determine the surface energy budget and a detailed characterization of surface, cloud and aerosol properties. Identical measurements have been carried out from the AWIPEV Base (German – French Research Base) in Ny-?lesund close to the open ocean while POLARSTERN remained in the sea ice. The observations of both surface stations have been closely coordinated with collocated airborne activities of the POLAR 5 and POLAR 6 AWI aircraft operating between both stations along the gradient of sea ice concentration as well as close to POLARSTERN. These airborne observations were supplemented by observations of the boundary layer structure (mean and turbulent quantities) from tethered balloon and several small Unmanned Airborne Vehicles UAV's, which were operated during the ice station nearby POLARSTERN. In parallel oceanographic, physical and biological research have been conducted on the drifting ice floe. Polar cod Boreogadus saida takes a key role in Arctic ecosystems, because it constitutes the staple food of seals and seabirds. Young polar cod live often associated with the underside of sea ice for foraging and protection from higher predators. Due to climate change, the extent of the under-ice habitat is decreasing. On PS 106/2, SiPCA (Survival of Polar Cod in a Chaning Arctic Ocean; PS 106/2) aimed to investigate the importance of sea ice for polar cod in the Barents Sea and the adjacent Arctic Ocean. We simultaneously sampled the spatial distribution of polar cod, its prey, its predators and other environmental parameters using fishing nets and ocean sensors. In parallel, we continued large parts of the continuous atmospheric sampling programme begun on PS 106/1, and investigated the physical and biogeochemical properties of sea ice and melt ponds during five sea ice stations. At the end of the expedition, we revisited the ice floe of PS 106/1 to collect more samples, conduct measurements, and to retrieve instruments left for continuous measurements during PS 106/2. The data obtained from this expedition will contribute to a more quantitative understanding of the sea ice-associated ecosystem, its importance for polar cod, physical and biogeochemical processes of sea ice and meltponts, as well as atmospheric dynamics in the Arctic. On May 24 2017 Polarstern set sails in Bremerhaven and reached a suitable nearly circular ice floe with a diamater of roughly 2.5 nautical miles (nm) at (82? 57.7' N, 10? 14.6' E) in the morning of June 3. On the way to the floe daily stops around noon were performed to sample water probes operating from a rubber boat and to perform radiation measurements. Further more, five SVP drifter and four ARGO floats were released on the way. After passing Longyearbyena daily CTD program was running until the end of PS106.1. On the ice floe camp continuous measurements of the energy budget at the surface and the state of the cloudy atmosphere was performed from June 4 to June 15. In parallel, sea ice physical, biological and biogeochemical measurements were carried out.

Messungen / Measurements