The scientific work during the expedition PS93.2 will support the time-series studies at the LTER (Long-Term Ecological Research) observatory HAUSGARTEN, where we document Global Change induced environmental variations on a polar deep-water ecosystem. This work is carried out in close co-operation between the HGF-MPG Joint Research Group on Deep-Sea Ecology and Technology, and the PEBCAO Group (Phytoplankton Ecology and Biogeochemistry in the Changing Arctic Ocean) at AWI and the Helmholtz Young Investigators Group SEAPUMP (Seasonal and regional food web interactions with the biological pump), representing a joint effort between AWI and the MARUM - Center for Marine Environmental Sciences, and the University of Bremen.
Together with the chief scientist Ursula Schauer from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), 49 scientists from 10 countries will conduct a “Trans-Arctic Survey of the Arctic Ocean in Transition” (TransArc II).
To enable distinguishing multi-annual variability from long-term trends, we repeat cruises to assess the regional distribution of the most important components of the system Arctic Ocean on a three to four-annual basis. Large-scale multi-disciplinary observations of the Eurasian sector of the Arctic have been conducted during the IPY 2007/2008 and during TransArc I in summer 2011. With TransArc II the same regions will now be sampled again.
With our program we will document whether not only the area but also the thickness of the sea ice continues to decrease like it did in the past decades; whether the advection of warmer waters from the Atlantic and from the Pacific goes on and how this is related to the sea ice decrease; whether the accumulation of fresh water, observed over the last decades, and the related changes of the surface layer structure, has possibly reached a turning point. All these changes go along with circulation changes and have an impact on the biogeochemical cycles and thereby on the organisms living in the ice, in the water column and on the sea floor. The mission of TransArc II is to investigate all these aspects of the Arctic Ocean system in an immediate context.
To this aim, we will work along long transects from the Atlantic influenced Eurasian shelf sea and basins up to the Pacific regime in the Canadian Basin and from ice-free waters into the packice of the Makarov Basin (see map). On these sections, we will sample all relevant components of the physical, the biogeochemical and the biological system. We will work from the ship, from helicopters and on ice floes to sample water, ice and the sea floor, and we will use autonomous platforms tethered on the bottom and on the sea ice.
A key component of the cruise contributes to the international GEOTRACES program, which aims at determining the distribution of trace elements and their isotopes in the ocean in order to understand their global cycle. Simultaneously to TransArc II, GEOTRACES cruises with US and Canadian icebreakers are taking place. This coordinated approach is a unique oppportunity for an Arctic-wide synoptic survey.