Abstracts

The Alfred Wegener Institute for Polar and Marine Research (AWI) has focused on Arctic research for many years.

Four recent research approaches using advanced technologies are presented here as an example.

1) Combining the institute’s icebreaking vessel R/V “Polarstern” with the French remotely operated vehicle (ROV) “Victor6000”, a powerful polar research facility was created. Besides visual and acoustic imaging of Arctic deep-sea environments, a variety of in situ experiments and micro sensor measurements have been conducted on the scientific maiden voyage of Victor6000 in order to investigate biological, geochemical, and physical gradients at the sediment-water interface. For example, benthic respiration and interfacial solute exchange is quantified under consideration of bottom current profiles using special devices designed for ROV manipulation.

2) ROV-based investigations are complemented by benthic lander technology. The latter is used for in situ flux measurements as well as for long term observations of benthic responses to large food falls and temporal variabilities of fluid discharge at an arctic mud volcano, respectively. A module concept allows to implement different payload modules onto the lander’s base frame.

3) Ice and bad weather conditions hamper shipborne oceanographic observations in arctic regions especially during the winter period. Oceanographic moorings provide a solution as they are able to record physical parameters throughout all seasons of the year. However, since the number of instruments is limited, observations can only be carried out at some distinct depth levels of the water column. To monitor temporal dynamics of descending water masses over the entire water column of the central Greenland Sea, a profiling CTD mooring has been developed. This “yo-yo” system monitors the water column of 4000 m once per day throughout a period of up to 400 days. The system complements oceanographic investigations annually conducted along 75°N and 79°N.

4) Evidences from submarine sonar measurements as well as from satellite observations suggest a considerable thinning and waning of the Arctic sea ice cover during the last decades. However, the limited time and space coverage of submarine sea-ice thickness data requires additional measurements which allow for more systematic thickness surveys. Therefore, we applied and operationalised electromagnetic (EM) induction sounding for ice thickness measurements. This geophysical technique, classically used on land to map ore or groundwater deposits, was implemented initially onto a sled towed over the ice. In a second step, the system was transferred into a helicopter-borne EM sensor ("EM-Bird"). First deployments in the Arctic yielded high resolution thickness data of good quality. With the EM-Bird, we will now be able to perform systematic large-scale studies of the ice thickness distribution, improving our ability to better judge observations and predictions of possible climate changes.