Modeling Thermodynamic Ice–Ocean Interactions at the Base of an Ice Shelf

Holland, David M.; Jenkins, Adrian

doi:10.1175/1520-0485(1999)029<1787:mtioia>2.0.co;2

Cited by 543 publications

(779 citation statements)

References 35 publications

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“…[26] The original basal melting scheme for the iceberg thermodynamics [see Bigg et al, 1997] has been replaced by the three-equation formulation of Holland and Jenkins [1999] for the turbulent transfer of heat beneath ice shelves. This formulation has been shown to produce more realistic iceberg meltwater fields in the Southern Ocean by Silva et al [2006] in iceberg model experiments.…”

Section: Iceberg Model Couplingmentioning

confidence: 99%

Sensitivity of the glacial ocean to Heinrich events from different iceberg sources, as modeled by a coupled atmosphere‐iceberg‐ocean model

2008

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[1] We introduce explicit icebergs from a dynamic and thermodynamic iceberg model into an intermediate complexity climate model, which includes the coupled atmosphere-ocean system. This modeling approach allows iceberg meltwater to be injected into the ocean on the basis of thermodynamical considerations along the iceberg trajectories. Icebergs are seeded from known ice sheets in both hemispheres. Adding icebergs to the present-day climate model has a minimal impact, but during the Last Glacial Maximum (LGM), Atlantic overturning strength is reduced by a third, while producing a model state that is consistent with a steady state climate. We test the sensitivity of the model at the LGM to additional Heinrich event-scale fluxes of icebergs from three possible sources: Hudson Strait, the Gulf of Saint Lawrence, and the Norwegian Channel Ice Stream (NCIS). The sensitivity of the ocean is similar for all locations, with differences dominated by the length of the iceberg meltwater pathways to the main ocean convection region. The NCIS events result in more variability and a distinctly different, more northerly, salinity anomaly. We compare these results to a more typical modeling approach, whereby meltwater is injected directly into the ocean at the iceberg source locations, and find that these floods overestimate the oceanic response compared to the iceberg events. Our results suggest that 0.3-0.4 Sv of additional freshwater flux, either as icebergs or freshwater, is required to shut down the North Atlantic meridional overturning, a larger freshwater flux than sometimes suggested because of the localized nature of the release of the freshwater.Citation: Levine, R. C., and G. R. Bigg (2008), Sensitivity of the glacial ocean to Heinrich events from different iceberg sources, as modeled by a coupled atmosphere-iceberg-ocean model, Paleoceanography, 23, PA4213,

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Section: Iceberg Model Couplingmentioning

confidence: 99%

Sensitivity of the glacial ocean to Heinrich events from different iceberg sources, as modeled by a coupled atmosphere‐iceberg‐ocean model

2008

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“…We generalize this discussion by defining a dimensionless distance from the wall, z + = u * ẑ /ν, where u * is the friction velocity,ẑ is the dimensional wall-normal coordinate (increasing away from the wall) and ν is the molecular viscosity. In this study a quadratic drag law is adopted such that u 2 * = C d U 2 , where C d = 1.5 × 10 −3 (Holland & Jenkins 1999) and U is the plume speed parallel to the shelf, averaged in the shelf-normal direction over the whole dynamic boundary layer.…”

Section: Frazil Precipitationmentioning

confidence: 99%

“…These, however, have focused on the modelling of direct melting and freezing at the ice shelf base (Holland & Jenkins 1999;Jenkins, Hellmer & Holland 2001) and, as yet, no GCM has incorporated or parameterized frazil ice or its deposition.…”

Section: Introductionmentioning

confidence: 99%

Frazil dynamics and precipitation in a water column with depth-dependent supercooling

Holland

Feltham

2005

J. Fluid Mech.

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When seawater becomes supercooled, collections of small ice crystals, known as frazil ice, form and grow. A model of frazil ice dynamics is presented that deals explicitly with the buoyant settling of frazil crystals onto an overlying surface. This yields further insight into transport associated with the ice pump mechanism, whereby ice is melted at depth and transferred to a shallower location as a result of the pressure variation of seawater's freezing temperature. The model is applied to a vertical cross-section through an Ice Shelf Water plume beneath Filchner-Ronne Ice Shelf, Antarctica, and helps to elucidate the depth-variation in its properties for the first time, as well as predicting the precipitation rate of frazil crystals. The model predicts that frazil ice should be preferentially located in a narrow layer near the ice shelf base as a result of the maximum supercooling there and an influx of crystals rising under their own buoyancy. The deposition of these crystals onto the ice shelf is governed by the balance between crystal rising and turbulent transfer of frazil away from the shelf, which is investigated in some detail.

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“…For an element in the interior of a large structure, the distance from the edge of the structure is large, and so using M b for the basal melt is not appropriate. Instead, the basal melt M s is determined using the three equation model for basal melt, which is a typical melting parametrization used beneath ice shelves [Holland and Jenkins, 1999], and has been used to parametrize melt rates beneath large icebergs in previous studies [Silva et al, 2006;Rackow et al, 2017].…”

Section: Journal Of Advances In Modeling Earth Systems 101002/2017msmentioning

confidence: 99%

Modeling tabular icebergs submerged in the ocean

Stern

Adcroft

Sergienko

et al. 2017

J Adv Model Earth Syst

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Large tabular icebergs calved from Antarctic ice shelves have long lifetimes (due to their large size), during which they drift across large distances, altering ambient ocean circulation, bottom‐water formation, sea‐ice formation, and biological primary productivity in the icebergs' vicinity. However, despite their importance, the current generation of ocean circulation models usually do not represent large tabular icebergs. In this study, we develop a novel framework to model large tabular icebergs submerged in the ocean. In this framework, tabular icebergs are represented by pressure‐exerting Lagrangian elements that drift in the ocean. The elements are held together and interact with each other via bonds. A breaking of these bonds allows the model to emulate calving events (i.e., detachment of a tabular iceberg from an ice shelf) and tabular icebergs breaking up into smaller pieces. Idealized simulations of a calving tabular iceberg, its drift, and its breakup demonstrate capabilities of the developed framework.

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Modeling Thermodynamic Ice–Ocean Interactions at the Base of an Ice Shelf

Cited by 543 publications

References 35 publications

Sensitivity of the glacial ocean to Heinrich events from different iceberg sources, as modeled by a coupled atmosphere‐iceberg‐ocean model

Sensitivity of the glacial ocean to Heinrich events from different iceberg sources, as modeled by a coupled atmosphere‐iceberg‐ocean model

Frazil dynamics and precipitation in a water column with depth-dependent supercooling

Modeling tabular icebergs submerged in the ocean

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