Weekly Reports Polarstern
The Expedition PS106 from Bremerhaven to Tromsø
The expedition PS 106 leaves Bremerhaven on May 24th, 2017. Its first destination is an ice floe situated deep enough in the central Arctic Ocean to allow for a two-week drift. During this drift, the atmospheric energy budget at ground level as well as the physical-chemical conditions of the cloud cover will be investigated (project PASCAL: Physical feedbacks of Arctic PBL, Seaice, Cloud And Aerosol; PS 106.1). After the drift station Polarstern will continue to Longyearbyen, from where it will set out for the expedition SiPCA (Survival of Polar Cod in a Chaning Arctic Ocean), where sea ice physics, physical oceanography and atmospheric science will be conducted. Expedition PS 106 concludes in Tromsø on July 20th, 2017.
The Polar Regions are important components in the global climate system. The widespread surface snow and ice cover in Polar Regions strongly impacts the atmospheric surface energy budget, which is tightly coupled to global atmospheric and oceanic circulations. The interaction of different Arctic feedback mechanisms is not yet completely understood. To address this issue, the project PASCAL (PS 106.1 and PS106.2) will use highly sophisticated instrumentation on board of Polarstern to determine the surface energy budget and a detailed characterization of surface, cloud and aerosol properties. Identical measurements are carried out from the AWIPEV Base (German – French Research Base) in Ny-Ålesund close to the open ocean while Polarstern will remain in the sea ice. The observations of both surface stations will be 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 will be supplemented by observations from tethered balloons and Unmanned Airborne Vehicles (UAV), which will be operated during the ice station nearby Polarstern. PASCAL and air-craft measurements are part of the Collaborative Research Initiative TR 172 (Arctic Amplification). In parallel with atmospheric studies, we will conduct oceanographic, physical and biological research on the drifting ice floe. The project TEMPO (Temporal Evolution of Melt POnd characteristics in different Arctic sea ice), conducted during both parts of the expedition, seeks to fill the knowledge gap about the temporal and spatial dynamics of melt ponds and their role in the Arctic climate and ecosystem.
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. SiPCA (PS 106.2) aims to investigate the importance of sea ice for polar cod in the Barents Sea and the adjacent Arctic Ocean. It is aimed to simultaneously sample the spatial distribution of polar cod, its prey, its predators and other environmental parameters using fishing nets and ocean sensors. The physical and biogeochemical properties of sea ice and melt ponds will be investigated during several sea ice stations. The data obtained from this expedition will help estimating the susceptibility of polar cod to climate change.