The spreading of Labrador Sea Water from the Labrador Sea to the Newfoundland Basin
Dagmar Kieke1, Kerstin Jochumsen2, Linn Schneider1, Igor Yashayaev3, Blair J W Greenan4, Nuno Serra2, Eugene Colbourne5, Monika Rhein6, Eirini Varotsou2 and Reiner Steinfeldt6, (1)University of Bremen, Bremen, Germany, (2)Universitat Hamburg, Hamburg, Germany, (3)Bedford Institute of Oceanography, Fisheries and Oceans Canada, Dartmouth, NS, Canada, (4)Bedford Institute of Oceanography, Dartmouth, NS, Canada, (5)Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, St. John's, NF, Canada, (6)University of Bremen, Institute of Environmental Physics, Bremen, Germany
Abstract:
Labrador Sea Water (LSW), the lightest component of the deep branch of the Atlantic Meridional Overturning Circulation (AMOC), has seen prominent changes throughout the most recent years. Convection activity considerably increased in the winters of 2014 and 2015 compared to previous years. As a consequence, a new fresh, cold, and relatively dense class of LSW formed during these winters spread within the Deep Western Boundary Current (DWBC) from the Labrador Sea towards the Flemish Cap and probably further downstream along the continental slope. The Flemish Cap presents a topographic obstacle that divides the southward LSW flow into two branches – the first branch enters Flemish Pass (sill depth 1200 m), and the second branch takes a detour around Flemish Cap towards the south. Several ship cruises carried out in early summers of 2013, 2014, and 2015 delivered hydrographic, velocity, and tracer measurements at various locations around Flemish Cap and in Flemish Pass. Here, we report on short-term and long-term changes in the properties of LSW as it leaves the Labrador Sea and enters the Newfoundland Basin to the south and east of Flemish Cap. We furthermore infer water mass transports obtained from the respective ship-based velocity measurements as well as from a mooring deployed in Flemish Pass during 2012-2013 and discuss them with respect to major features of the complex circulation regime.
