Monitoring ice thickness in Fram Strait

Vinje, Torgny; Nordlund, Nina; Kvambekk, Ånund Sigurd

doi:10.1029/97jc03360

Cited by 218 publications

(264 citation statements)

References 26 publications

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“…The model value of 1712 km 3 yr 21 is ;64% of the climatological value. The export of sea ice through Fram Strait has been fairly extensively examined (Vinje et al 1998;Kwok et al 2004), with the climatology value of 2300 km 3 yr 21 in good agreement with the 2598 km 3 yr 21 from the model. Accurate measurements of the freshwater fluxes through the Canadian Archipelago are more difficult to make owing to the remoteness and large area covered by this complex network of channels, leading to a wide range of estimates in the literature from 1700 to 3500 km 3 yr 21 .…”

Section: The Arctic Freshwater Budgetmentioning

confidence: 69%

Simulated Response of the Arctic Freshwater Budget to Extreme NAO Wind Forcing

et al. 2009

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The authors investigate the response of the Arctic Ocean freshwater budget to changes in the North Atlantic Oscillation (NAO) using a regional-ocean configuration of the Massachusetts Institute of Technology GCM (MITgcm) and carry out several different 10-yr and 30-yr integrations. At 1 / 6 8 (;18 km) resolution the model resolves the major Arctic transport pathways, including Bering Strait and the Canadian Archipelago. Two main calculations are performed by repeating the wind fields of two contrasting NAO years in each run for the extreme negative and positive NAO phases of 1969 and 1989, respectively. These calculations are compared both with a control run and the compiled observationally based freshwater budget estimate of Serreze et al.The results show a clear response in the Arctic freshwater budget to NAO forcing, that is, repeat NAO negative wind forcing results in virtually all freshwater being retained in the Arctic, with the bulk of the freshwater content being pooled in the Beaufort gyre. In contrast, repeat NAO positive forcing accelerates the export of freshwater out of the Arctic to the North Atlantic, primarily via Fram Strait (;900 km 3 yr 21 ) and the Canadian Archipelago (;500 km 3 yr 21 ), with a total loss in freshwater storage of ;13 000 km 3 (15%) after 10 yr. The large increase in freshwater export through the Canadian Archipelago highlights the important role that this gateway plays in redistributing the freshwater of the Arctic to subpolar seas, by providing a direct pathway from the Arctic basin to the Labrador Sea, Gulf Stream system, and Atlantic Ocean.The authors discuss the sensitivity of the Arctic Ocean to long-term fixed extreme NAO states and show that the freshwater content of the Arctic is able to be restored to initial values from a depleted freshwater state after ;20 yr.

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Section: The Arctic Freshwater Budgetmentioning

confidence: 69%

Simulated Response of the Arctic Freshwater Budget to Extreme NAO Wind Forcing

et al. 2009

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“…We note that this on-shelf ice flux is similar to (about one-half) that estimated by Woodgate, Aagaard, Muench, Gunn, Björk, Rudels, Roach and Schauer (in press) for the Barents Sea in 1993-94. We note also that the 0.005 Sv on-shelf ice flux is only about 5% of the estimated ice transport southward through Fram Strait (Vinje, Nordlund and Kvambekk, 1998), and so the flux of ice onto the Barents shelf does not greatly affect estimates of total ice export from the Arctic Ocean. The heat flux needed to melt the ice is also small, only 1.6 x 10 12 W, whereas the temperature decrease in the Atlantic water transformation represents a much larger heat loss of 38 x 10 12 W. Therefore, on average, only about 4% of the oceanic heat loss represented by the transformation of Atlantic water on the shelf is used to melt ice.…”

Section: An Example: Transformation Of the Barents Sea Throughflowmentioning

confidence: 99%

Some thoughts on the freezing and melting of sea ice and their effects on the ocean

Aagaard

Woodgate

2001

Ocean Modelling

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Abstract. The high-latitude freezing and melting cycle can variously result in haline convection, freshwater capping, or freshwater injection into the interior ocean. An example of the latter process is a secondary salinity minimum near 800 m depth within the Arctic Ocean that results from the transformation on the Barents Sea shelf of Atlantic water from the Norwegian Sea and its subsequent intrusion into the Arctic Ocean. About onethird of the freshening on the shelf of that initially saline water appears to result from ice melt, although the actual sea ice flux is small, only about 0.005 Sv. A curious feature of this process is that water distilled at the surface of the Arctic Ocean by freezing ends up at mid-depth in the same ocean. This is a consequence of the ice being exported southward onto the shelf, melted, and then entrained into the northerly Barents Sea throughflow that subsequently sinks into the Arctic Ocean. Prolonged reduction in sea ice in the region and in the concomitant freshwater injection would likely result in a warmer and more saline interior Arctic Ocean below 800 m. Some Thoughts on the Freezing and Melting of Sea Ice and TheirEffects on the Ocean K. Aagaard and R. A. WoodgateIntroduction Evaporation and precipitation rates over the Arctic Ocean are quite low, respectively about 5-10 cm yr -1 and 20-30 cm yr -1 in liquid water equivalent (Barry and Serreze, 2000). The primary cycling of freshwater in the Arctic Ocean is therefore instead accomplished by the freezing and melting of sea ice, for which characteristic rates are about 100 cm yr -1 and 50 cm yr -1 , respectively (Steele and Flato, 2000). If the ice drifts during the long intervals between the phase changes, the result is a net local distillation, since the freezing process expels the majority of the salt in the freezing water into the underlying ocean. This freezing and melting of sea ice, with their accompanying salinity changes, provide buoyancy forcing that is particularly effective in influencing the circulation because of the primary control of density by salinity at the prevailing low temperatures. For example, Holland, Mysak and Oberhuber (1996) concluded that buoyancy forcing is critical to maintaining the mixed layer circulation in the Arctic Ocean. The present note points to the range of buoyancy forcing that is possible in the high-latitude ocean. We begin with an example from the northern North Atlantic extension, viz., the cooling and freshening of the Atlantic water on the Barents shelf. We then place this process in the broader context of interactions between sea ice and the ocean. The intent is to thereby call attention to some appropriate, and even necessary, considerations in modelling the high-latitude ocean, especially in regard to the possible restructuring of ocean properties under altered climatic conditions.

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“…Volume transport for the EGC is ϳ1 Sv for the upper 200 m (Burke et al 1987;Foldvik et al 1988), which we use to represent PSW export. An annual average of about 0.09 Sv of ice is exported through Fram Strait (Vinje et al 1998). Using an average DOC value of 80 M for the EGC and 107 M for ice (similar to average values measured in Arctic sea-ice cores; Thomas et al 1995), we estimate an annual export through the Fram Strait of 2.9-10.3 Tg terrigenous DOC in the upper 200 m of the EGC.…”

Section: Export Of Terrigenous Udom In Arcticmentioning

confidence: 99%

Major flux of terrigenous dissolved organic matter through the Arctic Ocean

Opsahl

Benner

Amon

1999

Limnology & Oceanography

300

271

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High‐latitude rivers supply the Arctic Ocean with a disproportionately large share of global riverine discharge and terrigenous dissolved organic matter (DOM). We used the abundance of lignin, a macromolecule unique to vascular plants, and stable carbon isotope ratios (δ13C) to trace the high molecular weight fraction of terrigenous DOM in major water masses of the Arctic Ocean. Lignin oxidation products in ultrafiltered DOM (UDOM; >1,000 Da) from Arctic rivers were depleted in syringyl relative to vanillyl phenols (S/V = 0.3–0.5) compared to UDOM in temperate and tropical rivers (S/V = 0.5–1.2), indicating that gymnosperm vegetation is a major source of terrigenous UDOM to the Arctic Ocean. High concentrations of lignin oxidation products (83–320 ng L−1) and a depletion of 13C (δ13C = −23.0 to −21.9) in UDOM throughout the surface Arctic Ocean indicate that terrigenous UDOM accounts for a much greater fraction of the UDOM in the surface Arctic (5–33%) than in the Pacific and Atlantic oceans (0.7–2.4%). In contrast, UDOM in deep water from the Arctic Ocean as well as waters from throughout the Greenland Gyre had relatively low concentrations of lignin oxidation products (24–45 ng L−1 ) and was enriched in 13C (δ13C = −21.0 to −20.8). Terrigenous UDOM has a relatively short residence (∼1–6 yr) in surface polar waters prior to export to the north Atlantic Ocean. Assuming that the bulk of Arctic‐derived DOM is compositionally similar to the UDOM fraction, we estimate that 12–41% of terrigenous DOM (2.9–10.3 Tg C yr−1 ) discharged by rivers to the Arctic Ocean is exported to the North Atlantic via surface waters of the East Greenland Current. It appears very little terrigenous DOM from the Arctic is incorporated into North Atlantic Deep Water and distributed globally via deep thermohaline circulation.

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Monitoring ice thickness in Fram Strait

Cited by 218 publications

References 26 publications

Simulated Response of the Arctic Freshwater Budget to Extreme NAO Wind Forcing

Simulated Response of the Arctic Freshwater Budget to Extreme NAO Wind Forcing

Some thoughts on the freezing and melting of sea ice and their effects on the ocean

Major flux of terrigenous dissolved organic matter through the Arctic Ocean

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