June 12, 2017: FB1 seminar

11:00, lecture hall west, Düsternbrooker Weg 20

Abstract:

For the past 19 years and ongoing, the western boundary current system of the Labrador Sea has been closely observed by the so-called 53°N Array, consisting of moorings and shipboard station data which measure the top-to-bottom flow field offshore from the Labrador shelf break. In order to calculate meaningful volume transports for the North Atlantic Deep Water (NADW) components, different methods, including gap filling procedures for deployment periods with suboptimal instrument coverage, were applied.

On average the Deep Western Boundary Current (DWBC) carries 30.2 ± 6.6 Sv of NADW southward, which are almost equally partitioned between Labrador Sea Water (LSW, 14.9 Sv ± 3.9) and Lower North Atlantic Deep Water (LNADW, 15.3 Sv ± 3.8).

The transport variability ranges from days to decades, with the most prominent multi-year fluctuations at interannual to near decadal time scales (± 5 Sv) in the LNADW overflow water mass. These long-term fluctuations appear to be in phase with the NAO-modulated wind fluctuations. The boundary current system off Labrador occurs as a conglomerate of nearly independent components, namely the shallow Labrador Current, the weakly sheared LSW range, and the deep baroclinic, bottom-intensified current core of the LNADW, all of which are part of the cyclonic Labrador Sea circulation. A weak counterflow seaward of the boundary current reduces the Deep Water export by 10 to 15%.

An update is given for the most recently recovered mooring data for 2014-2016.

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