PS101 KARASIK

We are now returning to the area to assess in an interdisciplinary study how the seamount and vents alter their environment, from hydrographic conditions to the microbial community structure. Allso, our research contributes to assessing the state of the Arctic Ocean system including the sea ice decline and the biogeochemical and biological functions within the central basins. To accomplish this, we will also exchange components of the FRAM Observatory infrastructure. The seamount work contributes to the research program “Geosphere Biosphere Interactions” of the Excellence Cluster MARUM of the University of Bremen. Two different research communities  - the deep-sea and space research communities - are joining forces to better understand how extreme environments under ice could be analogues to distant planetary bodies. Hence, this expedition involves the instrumentation and experience of the ROBEX and PSTAR (“Planetary Science and Technology Through Analog Research Program) NASA/WHOI teams. We are 46 scientists and technicians (Fig. 2) from five different countries during the PS101 mission from 09.09. to 23.10.2016.

We left the port of Tromsø midday of the 09.09.2016 and enjoyed the beautiful Norwegian coastline for a few hours before reaching the open sea. There was much equipment to be unpacked and installed in all the labs of Polarstern. A Major initial piece of work was to install two newly delivered fiber optic cables and to get them to function with our new telemetry-guided instruments, which was a challenge for the crew and scientists alike. typo3/#_msocom_1 The research program started with the deployment of several oceanographic buoys for French colleagues. On 11.09.16 we tested our telemetry-guided equipment at a station East of Svalbard, including the zooplankton recorder LOKI and the Ocean Floor Observation System OFOS.  The latter was delivered just prior to the commencement of the cruise, after having received an upgrade with two sonar systems to map the ocean floor in ice-covered seas. The first images of the seafloor, taken from 250m water depth on the Norwegian shelf, showed abundant benthic life and an undisturbed seafloor, making the mouth water for the potential discoveries to be made at Karasik seamount in the forthcoming days.

We reached the sea ice margin at 81.5°N at midnight of the 11.-12.09.16. A closely spaced oceanography transect was started using underway measurements along 30°E longitude, down the slope into the Nansen Basin. Free falling xCTD probes can be used to sample salinity and temperature in the upper 1000 m while the ship is moving at full speed. On 13.09.16 we reached the deep basin at 4000 m and completed a full-depth CTD-cast with water sampling, of which every milliliter was used by the onboard scientists in analyses. The oceanographers detected a further warming of the deep waters compared to 2015 – an ongoing process they have been monitoring for more than a decade (Fig. 3).

The sea-ice observations made during our missions will contribute to the better assessment of the Arctic change and its ecosystem consequences. We will deploy various autonomous sea ice buoys that will send year-round physical and biogeochemical data to researchers and data archives onshore, even when no research vessel is within the Arctic. The experienced Arctic researchers on board – and also those following us at expedition.awi.de from home – have noticed already, by our speedy course through the ice, that something has changed in the far North. We have an average velocity of 6 knots through the dense autumn ice – a speed made possible by the substantial thinning of the sea ice and the loss of multiyear ice during the past few years. In fact, the sea ice physicists on board estimate that 2016 sets a new record low of sea ice volume in the Arctic since the onset of satellite observations. The new ROV BEAST which we used for the first time at the first ice-station of this mission (Fig .4) transmits images from the melted underside of the ice floes. Also, we encounter vast areas of open water, which are beginning to freeze during the last few days. We find these open regions easily via the the new sea ice geographical information system – short: ICEGIS - we are currently testing onboard (Fig. 5). It displays overlaying  maps of satellite and radar images of the ice, and shows the predictions of computer drift models and wind velocities over our seafloor maps. It is a great tool for way finding and for planning sampling simultaneous research work both on and under ice, and we send grateful thanks to all the programmers involved in realizing this innovation.