The scientific motivation for this task, and the underlying scientific questions, are found in the description of Tasks 3.5, 3.6, 3.8 and 3.9. These are the tasks that will receive data from the task described here, which is also connected to task 1.7 described above.

We plan to use the Norwegian coastguard ice breaker KV Svalbard as a platform for two drift stations, taking place in 2007 (three weeks) and 2008 (six weeks). The vessel will penetrate into the Transpolar Drift to about 80°-81° N. The ship will then partly drift and partly steam south along the lower limb of the Transpolar Drift, across the DAMOCLES freshwater and ice thickness observational array at 79° N, and south to the corresponding array at 74° N. Helicopter sections (ice thickness profiling (Gerland et al. in press), short ice stations with oceanographic measurements and snow and ice surveys) are made across the drift stream. The sampling will be a combination of stations moored to selected ice floes, and stations during the southward steaming. KV Svalbard has earlier supported NPI in Fram Strait during winter conditions, and has demonstrated its ability to perform well in heavy multiyear ice.

The data sampled under this task should contribute to the basis for our understanding of biogeochemical cycling and food-web functions (task 3.5). It should also contribute to the data base for studies of the sea ice feedback mechanism (Task 3.6): Along with the Tara and NP-35 instrumentation (Task 1.7), this part of iAOOS Norway will cover the annual cycle of the observed parameters along the entire Transpolar Drift length, from its origin, through Fram Strait and well into the receiving basins. The third main component under the proposed campaigns is addressing the export of freshwater through Fram Strait: the strength and along-path evolution of sea ice, freshwater and volume transport of the East Greenland Current and Transpolar Drift as it exits the Arctic - the fate of the freshwater. The latter must be seen in connection with the freshwater observational arrays (Task 1.9). It basically consists of a mapping of the winter/spring time TS and current fields across the EGC and wide East Greenland Shelf, along with an associated mapping of sea ice thickness distributions.

For the sea ice thickness mapping from helicopter (see figure above) we plan to use the AWI EM bird (cf. attached letter of intent of collaboration from C. Haas, AWI) and corresponding in situ drilling and ground electromagnetic profiling. The data obtained during the drift-station work will be combined and integrated with mooring data from NPIs long-term measurements (Vinje et al. 1998, Hansen et al. 2004; Holfort and Hansen 2005).