North Atlantic Current and Deep Western Boundary Current Transports - Cruise No. M82/2 - August 04 - September 01, 2010 - St. John’s (Canada) - Pta. Delgada (Portugal) (English)

The cruise is part of the German joint research project ‘Nordatlantik’ and is supported by the German Ministry of education and research, BMBF, and the Deutsche Forschungsgemeinschaft (DFG). The close in-project collaboration between the Bremen University (M. Rhein) and the Bundesamt fuer Seeschifffahrt und Hydrographie, BSH (B. Klein) is extended to the Woods Hole Oceanographic Institution, WHOI (A. Bower). The Woods Hole efforts are dedicated to obtain time series of transport and water mass characteristics through the Charlie Gibbs Fracture Zone by moored sensors. The eight WHOI moorings will be recovered in 2012. The oceanography department of the Bremen University operates a subpolar North Atlantic observing system, comprised of the following long term measurements: biennial change in the production rate of Labrador Sea Water (since 1997), the transport variability of the subpolar gyre (since 2006), the export of deep water in the Western Boundary Current (since 2009), and the fluctuations of the North Atlantic current inflow across 47°N (since 2010). The objectives of cruise M82/2 (see chapter 3 Research Programme) contributed to this observing system. They were fully met, except that the 47°N section (former WOCE section A2) could not be completed, but was abandoned at 14°48’W. Six moorings were successfully retrieved, and fourteen moorings deployed. The 38kHz vm-ADCP worked exceptionally well and monitored continually the velocity field in the upper 1600 m. The very favourable weather conditions and the improved stability of the METEOR also led to an excellent data quality for the CTDO2 and LADCP profiles. From the three PIES (inverted echo sounders with pressure sensor), which were deployed since August 2006, two were recovered successfully. This is the longest time, a PIES was ever deployed at depth without interruption and recovered. Despite several tries, the third PIES did not respond to the release command, and remained at the bottom. The telemetric reading of the two PIES that were deployed in July 2009 and November 2009, respectively, and were supposed to stay in their mooring positions, worked well.