The turbulent wall plume from a vertically distributed source of buoyancy

McConnochie, Craig; Kerr, Ross C.

doi:10.1017/jfm.2015.691

Cited by 23 publications

(42 citation statements)

References 17 publications

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“…E 0 is not accurately known and can be regarded as a tunable parameter within a certain range of values known from previous work. Laboratory experiments for a pure vertical plume, model studies and theoretical considerations give a broad range for E 0 , from 0.036 to 0.16 (Jenkins, 2011;Kaye and Linden, 2004;Mugford and Dowdeswell, 2011;Kimura et al, 2014;Carroll et al, 2015;McConnochie and Kerr, 2016). Nevertheless, glacier slope sin α can vary by 2 orders of magnitude so that regardless of the value of E 0 within the reported range, tidewater glaciers (sin α ∼ 1) are characterized by a high-entrainment regime, while glaciers Table 2.…”

Section: Entrainment Ratementioning

confidence: 95%

Simple models for the simulation of submarine melt for a Greenland glacial system model

2018

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Abstract. Two hundred marine-terminating Greenland outlet glaciers deliver more than half of the annually accumulated ice into the ocean and have played an important role in the Greenland ice sheet mass loss observed since the mid1990s. Submarine melt may play a crucial role in the mass balance and position of the grounding line of these outlet glaciers. As the ocean warms, it is expected that submarine melt will increase, potentially driving outlet glaciers retreat and contributing to sea level rise. Projections of the future contribution of outlet glaciers to sea level rise are hampered by the necessity to use models with extremely high resolution of the order of a few hundred meters. That requirement in not only demanded when modeling outlet glaciers as a stand alone model but also when coupling them with highresolution 3-D ocean models. In addition, fjord bathymetry data are mostly missing or inaccurate (errors of several hundreds of meters), which questions the benefit of using computationally expensive 3-D models for future predictions. Here we propose an alternative approach built on the use of a computationally efficient simple model of submarine melt based on turbulent plume theory. We show that such a simple model is in reasonable agreement with several available modeling studies. We performed a suite of experiments to analyze sensitivity of these simple models to model parameters and climate characteristics. We found that the computationally cheap plume model demonstrates qualitatively similar behavior as 3-D general circulation models. To match results of the 3-D models in a quantitative manner, a scaling factor of the order of 1 is needed for the plume models. We applied this approach to model submarine melt for six representative Greenland glaciers and found that the application of a line plume can produce submarine melt compatible with observational data. Our results show that the line plume model is more appropriate than the cone plume model for simulating the average submarine melting of real glaciers in Greenland.

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Section: Entrainment Ratementioning

confidence: 95%

Simple models for the simulation of submarine melt for a Greenland glacial system model

2018

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“…The interface between this meltwater layer and the unmodified ambient fluid below will hereafter be referred to as the first front. Conductivitytemperature traverses were performed every 20 min to measure the propagation of the first front during an experiment (McConnochie & Kerr 2016). All measurements of interface temperature, ablation velocity and plume velocity were made below the first front where the far-field temperature and salinity were constant to within 0.2 • C and 0.2 wt% NaCl respectively.…”

Section: Methodsmentioning

confidence: 99%

“…The maximum plume velocity was measured to within 5 % using the shadowgraph particle tracking velocimetry (shadowgraph PTV) technique described in McConnochie & Kerr (2016). Shadowgraph PTV is an adaptation of traditional PTV where turbulent eddies are tracked instead of particles.…”

Section: Methodsmentioning

confidence: 99%

“…In a homogeneous fluid, McConnochie & Kerr (2016) showed that the top-hat plume buoyancy can be described by…”

Section: Plume Buoyancymentioning

confidence: 99%

“…They found that the plume velocity should scale like z 1/3 , where z is the height measured from where the plume becomes turbulent. McConnochie & Kerr (2016) (2016) developed a complete top-hat model of the turbulent wall plume that forms next to a distributed source of buoyancy in a homogeneous ambient fluid. Of particular interest to this study, it was found that the maximum vertical velocity, w, in the wall plume can be described by…”

Section: Introductionmentioning

confidence: 99%

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The effect of a salinity gradient on the dissolution of a vertical ice face

McConnochie

Kerr

2016

J. Fluid Mech.

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We investigate experimentally the effect of stratification on a vertical ice face dissolving into cold salty water. We measure the interface temperature, ablation velocity and turbulent plume velocity over a range of salinity gradients and compare our measurements with results of similar experiments without a salinity gradient We observe that stratification acts to reduce the ablation velocity, interface temperature, plume velocity and plume acceleration. We define a stratification parameter, S = N 2 Q/Φ o , that describes where stratification will be important, where N is the Brunt-Väisälä frequency, Q is the height-dependent plume volume flux and Φ o is the buoyancy flux per unit area without stratification. The relevance of this stratification parameter is supported by our experiments, which deviate from the homogeneous theory at approximately S = 1. Finally, we calculate values for the stratification parameter at a number of ice shelves and conclude that ocean stratification will have a significant effect on the dissolution of both the Antarctic and Greenland ice sheets.

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Nonlinear response of iceberg side melting to ocean currents

FitzMaurice

Cenedese

Straneo

2017

Geophysical Research Letters

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Icebergs calving into Greenlandic Fjords frequently experience strongly sheared flows over their draft, but the impact of this flow past the iceberg is not fully captured by existing parameterizations. We present a series of novel laboratory experiments to determine the dependence of submarine melting along iceberg sides on a background flow. We show, for the first time, that two distinct regimes of melting exist depending on the flow magnitude and consequent behavior of melt plumes (side‐attached or side‐detached), with correspondingly different meltwater spreading characteristics. When this velocity dependence is included in melt parameterizations, melt rates estimated for observed icebergs in the attached regime increase, consistent with observed iceberg submarine melt rates. We show that both attached and detached plume regimes are relevant to icebergs observed in a Greenland fjord. Further, depending on the regime, iceberg meltwater may either be confined to a surface layer or distributed over the iceberg draft.

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The turbulent wall plume from a vertically distributed source of buoyancy

Cited by 23 publications

References 17 publications

Simple models for the simulation of submarine melt for a Greenland glacial system model

Simple models for the simulation of submarine melt for a Greenland glacial system model

The effect of a salinity gradient on the dissolution of a vertical ice face

Nonlinear response of iceberg side melting to ocean currents

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