A Model for the Thickness and Salinity of the Upper Layer in the Arctic Ocean and the Relationship between the Ice Thickness and Some External Parameters

Stigebrandt, Anders

doi:10.1175/1520-0485(1981)011<1407:amftta>2.0.co;2

Cited by 102 publications

(94 citation statements)

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“…The results are obtained using present-day conditions in the Arctic; i.e. A z 9 Â 10 12 m 2 , e z 10 À3 W m À2 , and Dr T z 0.2 kg m À3 (values are from (Jakobsson, 2002;Stigebrandt, 1981). The present-day freshwater input to the Arctic is about 0.28 Sv of which 0.09 exits through the Canadian Archipelago (Dickson et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

“…One possibility is that Polar Surface Water, forming a cold halocline, extended to deeper water depths and consequently forced the Atlantic water deeper. The depth of the cold halocline is primarily controlled by the freshwater input from rivers and by windinduced vertical mixing acting to force the buoyant freshwater downward (Stigebrandt, 1981). Perhaps counter-intuitively, a weaker freshwater input results in a deeper halocline (Nilsson and Wallin, 2010;Stigebrandt, 1981).…”

Section: The Role Of the Atlantic Water Influx And The Arctic Ocean Cmentioning

confidence: 99%

“…The depth of the cold halocline is primarily controlled by the freshwater input from rivers and by windinduced vertical mixing acting to force the buoyant freshwater downward (Stigebrandt, 1981). Perhaps counter-intuitively, a weaker freshwater input results in a deeper halocline (Nilsson and Wallin, 2010;Stigebrandt, 1981). The MIS 6 Arctic Ocean likely received substantially less freshwater because the hydrological cycle is generally weaker in colder climates (Held and Soden, 2006) and specifically the rivers ending in the Barents and Kara Seas were blocked by a very large Eurasian Ice Sheet (Svendsen et al, 2004).…”

Section: The Role Of the Atlantic Water Influx And The Arctic Ocean Cmentioning

confidence: 99%

“…The physics controlling the cold halocline can be examined with an analytical two-layer model (Nilsson and Wallin, 2010;Stigebrandt, 1981) consisting of an upper-layer halocline situated above and interacting with a layer of Atlantic water. The equatorward volume transport in the cold halocline, exported to the Atlantic, is denoted M and is much larger than the freshwater input F to the upper layer in the Arctic Ocean.…”

Section: Appendix 1 a Conceptual Model Of The Arctic Ocean Cold Halomentioning

confidence: 99%

“…The volume of the upper halocline layer, given by its surface area (A) multiplied by its depth (H), is in a steady state determined by a balance between the equatorward volume export and the windinduced mixing that acts to deepen the upper layer by incorporating Atlantic water. The export of water is assumed to be geostropically controlled (Stigebrandt, 1981), whereas the upwelling of the Atlantic water into the halocline layer is taken to be proportional to the energy input from the wind to turbulent mixing (denoted e per unit area) and inversely proportional to the halocline depth and the density difference between the halocline and the Atlantic layer (Dr) (Kato and Phillips, 1969). Solving for the steady-state upper-layer depth and the volume export, one obtains (Nilsson and Wallin, 2010) …”

Section: Appendix 1 a Conceptual Model Of The Arctic Ocean Cold Halomentioning

confidence: 99%

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An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

Nilsson

O’Regan

Backman

et al. 2010

Quaternary Science Reviews

119

118

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a b s t r a c tThe hypothesis of floating ice shelves covering the Arctic Ocean during glacial periods was developed in the 1970s. In its most extreme form, this theory involved a 1000 m thick continuous ice shelf covering the Arctic Ocean during Quaternary glacial maxima including the Last Glacial Maximum (LGM). While recent observations clearly demonstrate deep ice grounding events in the central Arctic Ocean, the ice shelf hypothesis has been difficult to evaluate due to a lack of information from key areas with severe sea ice conditions. Here we present new data from previously inaccessible, unmapped areas that constrain the spatial extent and timing of marine ice sheets during past glacials. These data include multibeam swath bathymetry and subbottom profiles portraying glaciogenic features on the Chukchi Borderland, southern Lomonosov Ridge north of Greenland, Morris Jesup Rise, and Yermak Plateau. Sediment cores from the mapped areas provide age constraints on the glaciogenic features. Combining these new geophysical and geological data with earlier results suggests that an especially extensive marine ice sheet complex, including an ice shelf, existed in the Amerasian Arctic Ocean during Marine Isotope Stage (MIS) 6. From a conceptual oceanographic model we speculate that the cold halocline of the Polar Surface Water may have extended to deeper water depths during MIS 6 inhibiting the warm Atlantic water from reaching the Amerasian Arctic Ocean and, thus, creating favorable conditions for ice shelf development. The hypothesis of a continuous 1000 m thick ice shelf is rejected because our mapping results show that several areas in the central Arctic Ocean substantially shallower than 1000 m water depth are free from glacial influence on the seafloor.

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Section: Discussionmentioning

confidence: 99%

Section: The Role Of the Atlantic Water Influx And The Arctic Ocean Cmentioning

confidence: 99%

Section: The Role Of the Atlantic Water Influx And The Arctic Ocean Cmentioning

confidence: 99%

Section: Appendix 1 a Conceptual Model Of The Arctic Ocean Cold Halomentioning

confidence: 99%

Section: Appendix 1 a Conceptual Model Of The Arctic Ocean Cold Halomentioning

confidence: 99%

See 3 more Smart Citations

An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

Nilsson

O’Regan

Backman

et al. 2010

Quaternary Science Reviews

119

118

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Response of Arctic Ocean stratification to changing river runoff in a column model

Nummelin

Smedsrud

2015

JGR Oceans

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A one-dimensional model of the atmosphere-ice-ocean column is used to study the effects of changing river runoff to the Arctic Ocean. River runoff is the largest contributor of freshwater to the Arctic and is expected to increase as the hydrological cycle accelerates due to global warming. The column model simulates the stratification of the Arctic Ocean reasonably well, capturing important features such as the fresh surface layer, the salty cold halocline, and the temperature maximum within the Atlantic Water layer. The model is run for 500 years with prescribed boundary conditions to reach steady state solutions. Increasing river runoff is found to strengthen the stratification and to produce a fresher and shallower surface mixed layer with warming (up to $1 C for a doubling of present-day runoff) in the Atlantic Water layer below. An important consequence is that the effect of the larger vertical temperature gradient is able to balance that of the stronger stratification and yield a close to constant vertical heat flux toward the surface. As a result, the sea ice response is small, showing only slight increase (up to $15 cm for a doubling of presentday runoff) in annual mean ice thickness. Limitations of the study include the idealized nature of the column model and uncertainties in the background vertical mixing within the Arctic Ocean.

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The response of the central Arctic Ocean stratification to freshwater perturbations

Pemberton

Nilsson

2016

JGR Oceans

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Using a state‐of‐the‐art coupled ice‐ocean‐circulation model, we perform a number of sensitivity experiments to examine how the central Arctic Ocean stratification responds to changes in river runoff and precipitation. The simulations yield marked changes in the cold halocline and the Arctic Atlantic layer. Increased precipitation yields a warming of the Atlantic layer, which primarily is an advective signal, propagated through the St. Anna Trough, reflecting air‐sea heat flux changes over the Barents Sea. As the freshwater supply is increased, the anticyclonic Beaufort Gyre is weakened and a greater proportion of the Arctic Ocean freshwater is exported via the Fram Strait, with nearly compensating export decreases through the Canadian Arctic Archipelago. The corresponding reorganization of the freshwater pool appears to be controlled by advective processes, rather than by the local changes in the surface freshwater flux. A simple conceptual model of the Arctic Ocean, based on a geostrophically controlled discharge of the low‐salinity water, is introduced and compared with the simulations. Key predictions of the conceptual model are that the halocline depth should decrease with increasing freshwater input and that the Arctic Ocean freshwater storage should increase proportionally to the square root of the freshwater input, which are in broad qualitative agreement with the sensitivity experiments. However, the model‐simulated rate of increase of the freshwater storage is weaker, indicating that effects related to wind forcing and rerouting of the freshwater‐transport pathways play an important role for the dynamics of the Arctic Ocean freshwater storage.

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A Model for the Thickness and Salinity of the Upper Layer in the Arctic Ocean and the Relationship between the Ice Thickness and Some External Parameters

Cited by 102 publications

References 0 publications

An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data

Response of Arctic Ocean stratification to changing river runoff in a column model

The response of the central Arctic Ocean stratification to freshwater perturbations

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