The Yermak Pass Branch: A Major Pathway for the Atlantic Water North of Svalbard?

Koenig, Zoé; Provost, Christine; Sennéchael, Nathalie; Garric, Gilles; Gascard, Jean‐Claude

doi:10.1002/2017jc013271

Cited by 40 publications

(97 citation statements)

References 44 publications

(77 reference statements)

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“…Although we show the northward flux of zooplankton across the Uncertain Fate region in Table 3, this zooplankton biomass may or may not reach the AB Koenig et al, 2017). Instead, zooplankton in the Uncertain Fate region might remain in recirculating AW, and could also be transported westward toward Greenland .…”

Section: Eddy Activity and Zooplankton Transportmentioning

confidence: 78%

“…The occurrence of carbon-rich species in the upper 600 m, where northward current velocities were strongest, resulted in large amounts of carbon being transported with the AW across the Inflow region. Furthermore, some of the zooplankton that is transported northward across the Uncertain Fate region may reach the AB, and likely more so in winter than in summer (Koenig et al, 2017). This suggest that the external input of zooplankton carbon, on the order of 34-50 kg C s −1 depending on the season (Table 3), is important for AWinfluenced areas of the AB during all seasons, including winter.…”

Section: Discussionmentioning

confidence: 99%

“…To the west of this continental slope current, to approximately 5 • E, the fate of the AW and included zooplankton is less certain. The AW flows northwards to the Yermak Plateau before either recirculating west-and southwards or entering the Arctic Basin across or around the perimeter of the plateau (Koenig et al, 2017). To the west of 5 • E the AW is likely recirculated.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Variation in Transport of Zooplankton Into the Arctic Basin Through the Atlantic Gateway, Fram Strait

et al. 2018

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The largest contribution of oceanic heat to the Arctic Ocean is the warm Atlantic Water (AW) inflow through the deep Fram Strait. The AW current also carries Atlantic plankton into the Arctic Basin and this inflow of zooplankton biomass through the Atlantic-Arctic gateway far exceeds the inflow through the shallow Pacific-Arctic gateway. However, because this transport has not yet been adequately quantified based on observational data, the present contribution is poorly defined, and future changes in Arctic zooplankton communities are difficult to project and observe. Our objective was to quantify the inflow of zooplankton biomass through the Fram Strait during different seasons, including winter. We collected data with high spatial resolution covering hydrography (CTD), currents (ADCP and LADCP) and zooplankton distributions (LOPC and MultiNet) from surface to 1,000 m depth along two transects crossing the AW inflow during three cruises in January, May and August 2014. Long-term variations (1997 in the AW inflow were analyzed based on moored current meters. Water transport across the inflow region was of the same order of magnitude during all months (January 2.2 Sv, May 1.9 Sv, August 1.7 Sv). We found a higher variability in zooplankton transport between the months (January 51 kg C s −1 , May 34 kg C s −1 , August 50 kg C s −1 ), related to seasonal changes in the vertical distribution of zooplankton. However, high abundances of carbon-rich copepods were observed in the AW inflow during all months. Surface patches with high abundances of C. finmarchicus, Microcalanus spp., Pseudocalanus spp., and Oithona similis clearly contributed to the advected biomass, also in winter. The data reveal that the phenology of species is important for the amount of advected biomass, and that the advective input of zooplankton carbon into the Arctic Basin is important during all seasons. The advective zooplankton input might be especially important for mesopelagic planktivorous predators that were recently observed in the region, particularly during winter. The inflow of C. finmarchicus with AW was estimated to be in the order of 500,000 metric tons C y −1 , which compares well to modeled estimates.

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Section: Eddy Activity and Zooplankton Transportmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal Variation in Transport of Zooplankton Into the Arctic Basin Through the Atlantic Gateway, Fram Strait

et al. 2018

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“…This study was supported by the Research Council of Norway through the project 229786. The work is based on the MSc study of Eivind Kolås (Kolås, 2017). We thank the crew and participants of the cruise HM 2015617.…”

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confidence: 99%

Hydrography, transport and mixing of the West Spitsbergen Current: the Svalbard Branch in summer 2015

Kolås

Fer

2018

Ocean Sci.

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Measurements of ocean currents, stratification and microstructure were made in August 2015, northwest of Svalbard, downstream of the Atlantic inflow in Fram Strait in the Arctic Ocean. Observations in three sections are used to characterize the evolution of the West Spitsbergen Current (WSC) along a 170 km downstream distance. Two alternative calculations imply 1.5 to 2 Sv (1 Sv = 10 6 m 3 s −1 ) is routed to recirculation and Yermak branch in Fram Strait, whereas 0.6 to 1.3 Sv is carried by the Svalbard branch. The WSC cools at a rate of 0.20 • C per 100 km, with associated bulk heat loss per along-path meter of (1.1 − 1.4) × 10 7 W m −1 , corresponding to a surface heat loss of 380-550 W m −2 . The measured turbulent heat flux is too small to account for this cooling rate. Estimates using a plausible range of parameters suggest that the contribution of diffusion by eddies could be limited to one half of the observed heat loss. In addition to shear-driven mixing beneath the WSC core, we observe energetic convective mixing of an unstable bottom boundary layer on the slope, driven by Ekman advection of buoyant water across the slope. The estimated lateral buoyancy flux is O(10 −8 ) W kg −1 , sufficient to maintain a large fraction of the observed dissipation rates, and corresponds to a heat flux of approximately 40 W m −2 . We conclude that -at least in summer -convectively driven bottom mixing followed by the detachment of the mixed fluid and its transfer into the ocean interior can lead to substantial cooling and freshening of the WSC.

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“…The absolute geostrophic currents toward the end of Section B (west of x = −75 km) , however, show currents toward the Arctic (positive values), which can be a signature of the 25 Yermak Pass branch. This branch is expected to be variable and weak in summer (Koenig et al, 2017). Between the Svalbard branch and (possibly) the Yermak Pass branch, a barotropic current is directed southwest, centered at x = −65 km (Fig.…”

mentioning

confidence: 99%

Hydrography, transport and mixing of the West Spitsbergen Current: the Svalbard Branch in summer 2015

Kolås¹,

Fer²

2018

Preprint

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The Yermak Pass Branch: A Major Pathway for the Atlantic Water North of Svalbard?

Cited by 40 publications

References 44 publications

Seasonal Variation in Transport of Zooplankton Into the Arctic Basin Through the Atlantic Gateway, Fram Strait

Seasonal Variation in Transport of Zooplankton Into the Arctic Basin Through the Atlantic Gateway, Fram Strait

Hydrography, transport and mixing of the West Spitsbergen Current: the Svalbard Branch in summer 2015

Hydrography, transport and mixing of the West Spitsbergen Current: the Svalbard Branch in summer 2015

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