No inter-gyre pathway for sea-surface temperature anomalies in the North Atlantic

Foukal, Nicholas P.; Lozier, M. Susan

doi:10.1038/ncomms11333

Cited by 32 publications

(34 citation statements)

References 30 publications

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“…Between the North Atlantic subtropical and subpolar gyres, only one surface drifter has traversed the Gulf Stream front in three decades of observations (Brambilla & Talley, ). The transport barrier is apparent only at the surface; model studies show that virtual drifters deployed in the subtropical regions are more likely to cross into the subpolar regions at depths of ∼

700

m (Burkholder & Lozier, ; Foukal & Lozier, ), or, more generally, along isopycnals (Bower & Rossby, ). Near‐surface heat transport is a small (10%) but important proportion of the net transport; within this proportion, the mesoscale geostrophic eddy contribution is believed to be negligible (Johns et al, ).…”

Section: Interocean Exchange Case Studiesmentioning

confidence: 99%

Surface Connectivity and Interocean Exchanges From Drifter‐Based Transition Matrices

McAdam

Sebille

2018

JGR Oceans

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Global surface transport in the ocean can be represented by using the observed trajectories of drifters to calculate probability distribution functions. The oceanographic applications of the Markov Chain approach to modeling include tracking of floating debris and water masses, globally and on yearly‐to‐centennial time scales. Here we analyze the error inherent with mapping trajectories onto a grid and the consequences for ocean transport modeling and detection of accumulation structures. A sensitivity analysis of Markov Chain parameters is performed in an idealized Stommel gyre and western boundary current as well as with observed ocean drifters, complementing previous studies on widespread floating debris accumulation. Focusing on two key areas of interocean exchange—the Agulhas system and the North Atlantic intergyre transport barrier—we assess the capacity of the Markov Chain methodology to detect surface connectivity and dynamic transport barriers. Finally, we extend the methodology's functionality to separate the geostrophic and nongeostrophic contributions to interocean exchange in these key regions.

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Section: Interocean Exchange Case Studiesmentioning

confidence: 99%

Surface Connectivity and Interocean Exchanges From Drifter‐Based Transition Matrices

McAdam

Sebille

2018

JGR Oceans

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“…Drifter and modeling studies of the modern ocean indicate a lack of warm surface water transport vis-à-vis a major warm water transport into the SPG via a subsurface (> 500 m) pathway into the Irminger Sea (Brambilla and Talley, 2006;Foukal and Lozier, 2016;Lozier, 2012). In contrast, hydrographic data from ocean cross sections indicate a transport of warm saline water between 10 and 1000 m water depth into the Irminger Basin and Labrador Sea (Sarafanov et al, 2012;Våge et al, 2011), with a recirculation and mixing zone of NAC waters into the SPG in the northwest corner of the SPG (Mertens et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Holocene evolution of the North Atlantic subsurface transport

Repschläger¹,

Garbe‐Schönberg²,

Weinelt³

et al. 2017

Clim. Past

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Abstract. Previous studies suggested that short-term freshening events in the subpolar gyre can be counterbalanced by advection of saline waters from the subtropical gyre and thus stabilize the Atlantic Meridional Overturning Circulation (AMOC). However, little is known about the inter-gyre transport pathways. Here, we infer changes in surface and subsurface transport between the subtropical and polar North Atlantic during the last 11 000 years, by combining new temperature and salinity reconstructions obtained from combined δ 18 O and Mg / Ca measurements on surface and subsurface dwelling foraminifera with published foraminiferal abundance data from the subtropical North Atlantic, and with salinity and temperature data from the tropical and subpolar North Atlantic. This compilation implies an overall stable subtropical warm surface water transport since 10 ka BP. In contrast, subsurface warm water transport started at about 8 ka but still with subsurface heat storage in the subtropical gyre. The full strength of intergyre exchange was probably reached only after the onset of northward transport of warm saline subsurface waters at about 7 ka BP, associated with the onset of the modern AMOC mode. A critical evaluation of different potential forcing mechanisms leads to the assumption that freshwater supply from the Laurentide Ice Sheet was the main control on subtropical to subpolar ocean transport at surface and subsurface levels.

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“…Downstream of the FC, westerlies drive Ekman transport into the subtropics. Almost no surface drifters deployed in the FC or Gulf Stream enter the subpolar gyre (Brambilla & Talley, ), and numerical trajectories and observed sea surface temperature confirm this lack of surface connectivity (Foukal & Lozier, ). Note that surface fluxes continually modify SW properties, so advective SW transport does not reflect water origins. IWE can interact with the western side through horizontal eddies or isopycnal mixing, or with the bottom layer via shear stress.…”

Section: Discussionmentioning

confidence: 99%

“…A similar magnitude (13.8 Sv) is obtained by applying SR91's conclusion that FC AMOC comes from AAIW and all SW. The results of Brambilla and Talley () and Foukal and Lozier (), however, strongly suggest that SW contributes little to AMOC. In any case, at least 3 Sv of AMOC remains unaccounted for.…”

Section: Discussionmentioning

confidence: 99%

“…Insight from the past decade of AMOC studies has not previously been applied to interpret the water mass constituents of the FC. In particular, recent studies of both the cold lower and warm upper limbs of the AMOC further north have been shown to be less continuous than anticipated (Bower et al, ; Foukal & Lozier, ). The implication of significant interior pathways and boundary‐interior interactions raises the possibility of significant modification by mixing.…”

Section: Introductionmentioning

confidence: 99%

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Florida Current Salinity and Salinity Transport: Mean and Decadal Changes

Szűts

Meinen

2017

Geophysical Research Letters

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The Florida Current (FC) contributes to Atlantic circulation by carrying the western boundary flow of the subtropical gyre and the upper branch of meridional overturning circulation. Repeated FC hydrographic (velocity, salinity, and temperature) sections during 1982–1987 and 2001–2015 characterize its water mass structure and associated transport variability. On average, FC volume transport comes from subtropical North Atlantic water (NAW, 44%), Antarctic Intermediate Water (AAIW, 14%), surface water (SW, 27%), and an indistinct source (Rem 15%), while salinity transport relative to the average salinity along 26°N comes from NAW (55%), AAIW (0.2%), SW (30%), and Rem (15%). From 1982–1987 to 2001–2015, NAW, AAIW, and Rem salinified by 0.03–0.16 g kg−1 and increased the salinity anomaly transport by 3%. These patterns imply that advective salt transport by the FC (1) is sensitive to subtropical North Atlantic variability and (2) is partially decoupled from the volumetric pathway of the upper overturning branch.

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No inter-gyre pathway for sea-surface temperature anomalies in the North Atlantic

Cited by 32 publications

References 30 publications

Surface Connectivity and Interocean Exchanges From Drifter‐Based Transition Matrices

Surface Connectivity and Interocean Exchanges From Drifter‐Based Transition Matrices

Holocene evolution of the North Atlantic subsurface transport

Florida Current Salinity and Salinity Transport: Mean and Decadal Changes

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