Wind‐Driven Coastal Upwelling and Downwelling in the Shelfbreak East Greenland Current

Håvik, Lisbeth; Våge, Kjetil

doi:10.1029/2018jc014273

Cited by 11 publications

(20 citation statements)

References 37 publications

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“…The property changes are indicative of a deepening of water masses, since the water overlying the near‐bottom MC is warmer and fresher (Harden et al., 2016). This reinforces the assertion of Håvik and Våge (2018) that downwelling favorable winds drive negative salinity anomalies on the upper Greenland slope north of DS. Note that this is similar to the barrier wind forcing seen by Harden et al.…”

Section: Advection Of Salinity Anomalies From the Shelfbreak Egc To T...supporting

confidence: 89%

The Annual Salinity Cycle of the Denmark Strait Overflow

et al. 2022

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The Denmark Strait Overflow (DSO) is an important source of dense water input to the deep limb of the Atlantic Meridional Overturning Circulation (AMOC). It is fed by separate currents from the north that advect dense water masses formed in the Nordic Seas and Arctic Ocean which then converge at Denmark Strait. Here we identify an annual salinity cycle of the DSO, characterized by freshening in winter and spring. The freshening is linked to freshening of the Shelfbreak East Greenland Current in the Blosseville Basin north of the Denmark Strait. We demonstrate that the East Greenland Current advects fresh pycnocline water above the recirculating Atlantic Water, which forms a low salinity lid for the overflow in Denmark Strait and in the Irminger Basin. This concept is supported by intensified freshening of the DSO in lighter density classes on the Greenland side of the overflow. The salinity of the DSO in the Irminger Basin is significantly correlated with northerly/northeasterly winds in the Blosseville Basin at a lag of 3–4 months, consistent with estimated transit times. This suggests that wind driven variability of DSO source water exerts an important influence on the salinity variability of the downstream DSO, and hence the composition of the deep limb of the AMOC.

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Section: Advection Of Salinity Anomalies From the Shelfbreak Egc To T...supporting

confidence: 89%

The Annual Salinity Cycle of the Denmark Strait Overflow

et al. 2022

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“…The proposed Rossby wave generation differs from the upwelling and downwelling off East Greenland described by Håvik and Våge (2018). Using the same ERA-Interim wind data as we do here, Håvik and Våge (2018) find that coastal upwelling and downwelling favorable winds cause across-shelf currents near the bottom that change the density below the East Greenland Current at 688N latitude. Analyzing wind climatology, Håvik et al (2017) suggest that this process diminishes in importance north of 728N latitude.…”

Section: Discussionmentioning

confidence: 44%

Ocean Circulation Connecting Fram Strait to Glaciers off Northeast Greenland: Mean Flows, Topographic Rossby Waves, and Their Forcing

Münchow

Schaffer

Kanzow

2020

Journal of Physical Oceanography

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From 2014 through 2016 we instrumented the ~80-km-wide Norske Trough near 78°N latitude that cuts across the 250-km-wide shelf from Fram Strait to the coast. Our measurements resolve a ~10-km-wide bottom-intensified jet that carries 0.27 ± 0.06 Sv (1 Sv ≡ 106 m3 s−1) of warm Atlantic water from Fram Strait toward the glaciers off northeast Greenland. Mean shoreward flows along the steep canyon walls reach 0.1 m s−1 about 50 m above the bottom in 400-m-deep water. The same bottom-intensified vertical structure emerges as the first dominant empirical orthogonal function that explains about 70%–80% of the variance at individual mooring locations. We interpret the current variability as remotely forced wave motions that arrive at our sensor array with periodicities longer than 6 days. Coherent motions with a period near 20 days emerge in our array as a dispersive topographic Rossby wave that propagates its energy along the sloping canyon toward the coast with a group speed of about 63 km day−1. Amplitudes of wave currents reach 0.1 m s−1 in the winter of 2015/16. The wave is likely generated by Ekman pumping over the shelfbreak where sea ice is always mobile. More than 40% of the along-slope ocean current variance near the bottom of the canyon correlates with vertical Ekman pumping velocities 180 km away. In contrast, the impact of local winds on the observed current fluctuations is negligible. Dynamics appear linear and Rossby wave motions merely modulate the mean flow.

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“…Previous studies of the EGC, and the AtOW that it transports, have mainly focused on the regions close to Fram and Denmark Straits (de Steur et al., 2009, 2014; Fahrbach et al., 2001; Foldvik et al., 1988; Harden et al., 2016; Håvik, Våge, et al., 2017; Håvik & Våge, 2018; Lin et al., 2020). Based on a long‐term (1997–2009) mooring array deployed south of Fram Strait (orange line in Figure 1), de Steur et al.…”

Section: Introductionmentioning

confidence: 99%

Wintertime Water Mass Transformation in the Western Iceland and Greenland Seas

et al. 2021

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Hydrographic and velocity data from a 2018 winter survey of the western Iceland and Greenland Seas are used to investigate the ventilation of overflow water feeding Denmark Strait. We focus on the two general classes of overflow water: warm, saline Atlantic‐origin Overflow Water (AtOW) and cold, fresh Arctic‐origin Overflow Water (ArOW). The former is found predominantly within the East Greenland Current (EGC), while the latter resides in the interior of the Iceland and Greenland Seas. Progressing north to south, the properties of AtOW in the EGC are modified diapycnally during the winter, in contrast to summer when along‐isopycnal mixing dominates. The water column response to a 10‐days cold‐air outbreak was documented using repeat observations. During the event, the northerly winds pushed the freshwater cap of the EGC onshore, and convection modified the water at the seaward edge of the current. Lateral transfer of heat and salt from the core of AtOW in the EGC appears to have influenced some of this water mass transformation. The long‐term evolution of the mixed layers in the interior was investigated using a 1‐D mixing model. This suggests that, under strong atmospheric forcing, the densest component of ArOW can be ventilated in this region. Numerous anti‐cyclonic eddies spawned from the EGC were observed during the winter survey, revealing that these features can play differing roles in modifying/prohibiting the open‐ocean convection.

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Wind‐Driven Coastal Upwelling and Downwelling in the Shelfbreak East Greenland Current

Abstract: The East Greenland Current is a major pathway for freshwater export from the Arctic Ocean

Cited by 11 publications

References 37 publications

The Annual Salinity Cycle of the Denmark Strait Overflow

The Annual Salinity Cycle of the Denmark Strait Overflow

Ocean Circulation Connecting Fram Strait to Glaciers off Northeast Greenland: Mean Flows, Topographic Rossby Waves, and Their Forcing

Wintertime Water Mass Transformation in the Western Iceland and Greenland Seas

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