On the origin and propagation of <scp>D</scp>enmark <scp>S</scp>trait overflow water anomalies in the <scp>I</scp>rminger <scp>B</scp>asin

Jochumsen, Kerstin; Köllner, Manuela; Quadfasel, Detlef; Dye, Stephen; Rudels, Bert; Valdimarsson, Héðinn

doi:10.1002/2014jc010397

Cited by 36 publications

(61 citation statements)

References 41 publications

(72 reference statements)

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“…3c), which was added to DSOW to agree with the cascading events occurring along DSOW pathway (e.g. Pickart et al, 2005;Falina et al, 2012;Jochumsen et al, 2015). The net volume transport of the shallow core of PIW across OVIDE 2014 is in agreement with previous estimates of around −2 Sv entering from the Arctic Ocean (barely −2 Sv reported by Pickart et al, 2005, and an average transport of −2.4 ± 0.3 Sv reported by Falina et al, 2012Falina et al, , for 2002Falina et al, -2004.…”

Section: Water Mass Volume Transports For 2014supporting

confidence: 78%

“…4f), supporting the existence of entrainment of East Greenland shelf waters into DSOW (e.g. Pickart et al, 2005;Falina et al, 2012;Jochumsen et al, 2015). PIW is also found on the continental shelves and slopes of Greenland and Canada, with the greatest contribution found on the Canadian shelf.…”

Section: Water Mass Distribution For 2014mentioning

confidence: 62%

“…Cascading events of Polar Intermediate Water (PIW) also affect DSOW in the Irminger Sea (e.g. Pickart et al, 2005;Falina et al, 2012;Jochumsen et al, 2015). ISOW forms after the Norwegian Sea waters overflow the IcelandScotland sills and entrain SPMW and LSW (van Aken and de Boer, 1995;Dickson et al, 2002;Fogelqvist et al, 2003).…”

Section: Hydrographic Features and General Circulationmentioning

confidence: 99%

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

et al. 2018

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Abstract. We present the distribution of water masses along the GEOTRACES-GA01 section during the GEO-VIDE cruise, which crossed the subpolar North Atlantic Ocean and the Labrador Sea in the summer of 2014. The water mass structure resulting from an extended optimum multiparameter (eOMP) analysis provides the framework for interpreting the observed distributions of trace elements and their isotopes. Central Waters and Subpolar Mode Waters (SPMW) dominated the upper part of the GEOTRACES-GA01 section. At intermediate depths, the dominant water mass was Labrador Sea Water, while the deep parts of the section were filled by Iceland-Scotland Overflow Water (ISOW) and North-East Atlantic Deep Water. We also evaluate the water mass volume transports across the 2014 OVIDE line (Portugal to Greenland section) by combining the water mass fractions resulting from the eOMP analysis with the absolute geostrophic velocity field estimated through a box inverse model. This allowed us to assess the relative contribution of each water mass to the transport across the section. Finally, we discuss the changes in the distribution and transport of water masses between the 2014 OVIDE line and the 2002-2010 mean state. At the upper and intermediate water levels, colder end-members of the water masses replaced the warmer ones in 2014 with respect to

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Section: Water Mass Volume Transports For 2014supporting

confidence: 78%

Section: Water Mass Distribution For 2014mentioning

confidence: 62%

Section: Hydrographic Features and General Circulationmentioning

confidence: 99%

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

et al. 2018

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“…Occasionally, the warm water peaks are even registered at the westernmost mooring DS22 (not shown). It is likely that the warm water originates in the vicinity of the sill, where bottom temperatures in the northward flow are within the observed range (e.g., see Figure 1 in Jochumsen et al, ). Further north of the sill, similarly high temperatures are not found below approximately 350 m (Jónsson & Valdimarsson, , ; Smith, ).…”

Section: Discussionmentioning

confidence: 81%

Mesoscale Eddies Observed at the Denmark Strait Sill

et al. 2019

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The Denmark Strait overflow is the major export route of dense water from the Arctic Mediterranean into the North Atlantic. At the Strait's shallow sill, the overflow is a bottom-intensified cold and dense plume, bound to the east by a thermal front formed with the warmer, northward flowing North Icelandic Irminger Current. More than two decades of observations at the sill show strong fluctuations of volume flux on daily time scales. To better understand the source of this variability, a five-mooring array was installed at the sill, capturing nearly 1 year of velocity and bottom temperature measurements at a high temporal and spatial resolution. Bottom temperature fluctuations that exceed 4 • C indicate a meandering of the front between the plume and the North Icelandic Irminger Current. Current vector rotation shows trains of alternating cyclones and anticyclones at the sill. An eddy crosses the sill every 3 to 6 days with a mean velocity of 0.4 m/s and a typical diameter of 30 to 40 km. The results suggest that anticyclones, with centers passing through the deepest part of the sill, may be responsible for periods of increased volume flux-also referred to as boluses and pulses in previous studies. Although the relationship between eddies, pulses, and boluses is still unclear, the results show that eddies are directly linked to fluctuations in the strength, thickness, and position of the overflow plume. Plain Language SummaryThe southward flow of dense water from the Arctic ocean plays a crucial role in global ocean circulation but is almost immediately constrained on its way south by a submarine ridge that connects Greenland, Iceland, the Faroe Islands, and Scotland. The southward flow is therefore forced to pass through several straits and up and over relatively shallow sills. Most of the flow passes over a sill in the Denmark Strait, located between Greenland and Iceland. In this study, we present observations from an array of instruments, which measure the southward flow as it passes over the Denmark Strait sill. The flow is characterised by trains of eddies (vortices), with an alternating sense of rotation; meaning a counterclockwise eddy is usually followed by a clockwise eddy. The eddies are 30 to 40 km wide and need about 1 day to pass over the sill. These eddies help to explain pronounced changes in the flow across the sill, as they can help either to speed up the flow or slow it down. The results of this study contribute to understanding mesoscale fluctuations, which influence local mixing processes and water mass transports.

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“…Using more than two decades' worth of hydrographic data from the region of the sill, Mastropole et al (2017) revealed that the Arctic-origin overflow water from the NIJ is found in the deepest part of the strait, whereas the Atlantic-origin overflow water resides above this and to the west, in the vicinity of the East Greenland shelf break (the constriction of the strait forces the shelf break and separated EGC branches to move closer to each other). Downstream of Denmark Strait these overflow waters entrain ambient water from the Irminger Basin, which significantly increases the transport and modifies the hydrographic properties of the dense water plume (e.g., Dickson et al 2008;Jochumsen et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The North Icelandic Jet and its relationship to the North Icelandic Irminger Current

Pickart¹,

Spall²,

Torres³

et al. 2017

j mar res

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Shipboard hydrographic and velocity sections are used to quantify aspects of the North Icelandic Jet (NIJ), which transports dense overflow water to Denmark Strait, and the North Icelandic Irminger Current (NIIC), which imports Atlantic water to the Iceland Sea. The mean transports of the two currents are comparable, in line with previous notions that there is a local overturning cell in the Iceland Sea that transforms the Atlantic water to dense overflow water. As the NIJ and NIIC flow along the north side of Iceland, they appear to share a common front when the bottom topography steers them close together, but even when they are separate there is a poleward flow inshore of the NIJ. The interannual variability in salinity of the inflowing NIIC is in phase with that of the outflowing NIJ. It is suggested, however, that the NIIC signal does not dictate that of the NIJ. Instead, the combination of liquid and solid freshwater flux from the east Greenland boundary can account for the observed net freshening of the NIIC to the NIJ for the densest half of the overturning circulation in the northwest Iceland Sea. This implies that the remaining overturning must occur in a different geographic area, consistent with earlier model results. The year-to-year variability in salinity of the NIJ can be explained by applying annual anomalies of evaporation minus precipitation over the Iceland Sea to a one-dimensional mixing model. These anomalies vary in phase with the wind stress curl over the North Atlantic subpolar gyre, which previous studies have shown drives the interannual variation in salinity of the inflowing NIIC.

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On the origin and propagation of Denmark Strait overflow water anomalies in the Irminger Basin

Cited by 36 publications

References 41 publications

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

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

Mesoscale Eddies Observed at the Denmark Strait Sill

The North Icelandic Jet and its relationship to the North Icelandic Irminger Current

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