Further intensification of deep convection in the Labrador Sea in 2016

Abstract

There has been a progressive deepening of winter convection in the Labrador Sea since 2012, with the individual profile maximum depth exceeding 1800 m since 2014 and reaching 2100 m in 2016. This increase, during repeated positive phases of the winter North Atlantic Oscillation (NAO), resembles that during the formation of the record depth (2500 m) Labrador Sea Water (LSW) class in 1987–1994, attributed to repeated positive NAO forcing having provided critical preconditioning. The 2012–2016 LSW class is one of the deepest and most persistent ever observed (back to 1938). Year‐round observations from profiling Argo floats since 2002 complemented by annual surveys are providing novel information on the seasonal‐to‐decadal evolution of LSW, such as its variable density, the recent multiyear preconditioning, and its 2016 density being the highest since the mid‐1990s. These findings should help international observation programs and numerical model studies investigating LSW influences on the subpolar North Atlantic and Atlantic Meridional Overturning Circulation.

Water mass distributions and transports for the 2014 GEOVIDE cruise in the North Atlantic

“…2.3) (e.g. Hansen et al, 2016;Yashayaev and Loder, 2017). For alternative comparative purposes, the water mass distribution using the same SWT properties as in García-Ibáñez et al (2015) is given in Fig.…”

“…This water mass redistribution responds both to the salinization of LSW (e.g. Yashayaev and Loder, 2017), and to the lower density of LSW formed in recent years that occupies shallower positions in the water column. García-Ibáñez et al (2015) also reported how the progressive salinization of LSW since the late 1990s resulted in a progressive decrease in LSW and increase in ISOW.…”

“…Sarafanov et al, 2012;García-Ibáñez et al, 2015;Yashayaev and Loder, 2017). The North Atlantic Current (NAC) carries warm and saline subtropical waters northwards, towards the north-eastern Atlantic Ocean (Fig.…”

“…Hansen et al, 2016;Yashayaev and Loder, 2017). We used 14 SWTs to solve the water mass structure along the GEOTRACES-GA01 section (Table 1, Fig.…”

Tracking Labrador Sea Water property signals along the Deep Western Boundary Current

“…As an alternative to dividing LSW into upper and deep classes, LSW can be split into year‐classes based on their history of formation and evolution. Four distinct LSW classes have been identified in the last three decades: LSW 1987–1994 , LSW 2000–2003 , LSW 2008 , and LSW 2012–2016 [ Lazier et al ., ; Yashayaev , ; Yashayaev and Loder , ]. In general, the density of a particular LSW class corresponds with the strength and persistence of winter cooling incurred through the years of its formation.…”