North Atlantic Current and Labrador Sea Water Circulation in the Subpolar North Atlantic - Cruise No. MSM43 - May 25 - June 27, 2015 - St. John's (Canada) - Nuuk (Greenland) (English)

The MARIA S. MERIAN cruise 43 (MSM43) was dedicated to physical oceanographic observations in the northwestern North Atlantic carried out by the Institute of Environmental Physics (IUP) at the University of Bremen in collaboration with the Bundesamt für Seeschifffahrt und Hydrographie (BSH) in Hamburg. The work program of MSM43 as part of the BMBF project RACE! (Regional Atlantic Circulation and Global Change) had the aim to study the regional circulation under global change. The objectives of the cruise were to service a long-term array (started in summer 2006) of moorings and bottom-mounted inverted echo sounders with pressure sensors (PIES) that measures the transport and water mass variability of the subpolar gyre, and to estimate the formation of Labrador Sea Water between 2013 and 2015 from the large scale distribution of transient tracers (SF6 and CFCs). During the cruise the data of all eight PIES were retrieved by acoustic telemetry, two PIES were released after the data recovery and one instrument was redeployed. Three moorings of the array were recovered, one east of Flemish Cap and two at the Mid-Atlantic Ridge (MAR). After servicing the instruments three moorings were deployed, one at the MAR and two east of Flemish Cap. Hydrographic, current, and tracer measurements were carried out at 109 stations. Water samples for the measurement of helium isotopes were taken on two sections close to the Greenland shelf to determine the amount of basal meltwater, and for the measurement of argon-39 on three station to test a new analyses technique at the University of Heidelberg. The major goals of the cruise were accomplished with the exception of the loss of two moorings at the MAR.