The Response of Ice Shelf Basal Melting to Variations in Ocean Temperature

Holland, Paul R.; Jenkins, Adrian; Holland, David M.

doi:10.1175/2007jcli1909.1

Cited by 275 publications

(334 citation statements)

References 48 publications

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“…6a). This is in accordance with satellite and timelapse camera images showing upwelling at these locations (Trusel et al, 2010;Kehrl et al, 2011;Darlington, 2015;How et al, 2017). Modelled surface melt and discharge at the northern outlet -in short northern discharge (ND) -starts 6 June and ends 1 October, while the discharge at the southern outlet (SD) starts 21 June and ends 22 August.…”

Section: Subglacial Discharge and Submarine Melt Ratessupporting

confidence: 85%

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Effects of undercutting and sliding on calving: a global approach applied to Kronebreen, Svalbard

et al. 2018

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Abstract. In this paper, we study the effects of basal friction, sub-aqueous undercutting and glacier geometry on the calving process by combining six different models in an offlinecoupled workflow: a continuum-mechanical ice flow model (Elmer/Ice), a climatic mass balance model, a simple subglacial hydrology model, a plume model, an undercutting model and a discrete particle model to investigate fracture dynamics (Helsinki Discrete Element Model, HiDEM). We demonstrate the feasibility of reproducing the observed calving retreat at the front of Kronebreen, a tidewater glacier in Svalbard, during a melt season by using the output from the first five models as input to HiDEM. Basal sliding and glacier motion are addressed using Elmer/Ice, while calving is modelled by HiDEM. A hydrology model calculates subglacial drainage paths and indicates two main outlets with different discharges. Depending on the discharge, the plume model computes frontal melt rates, which are iteratively projected to the actual front of the glacier at subglacial discharge locations. This produces undercutting of different sizes, as melt is concentrated close to the surface for high discharge and is more diffuse for low discharge. By testing different configurations, we show that undercutting plays a key role in glacier retreat and is necessary to reproduce observed retreat in the vicinity of the discharge locations during the melting season. Calving rates are also influenced by basal friction, through its effects on near-terminus strain rates and ice velocity.

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Section: Subglacial Discharge and Submarine Melt Ratessupporting

confidence: 85%

“…Plumes of turbid meltwater, fed by subglacial discharge, are observed adjacent to the glacier terminus during the melt season (Trusel et al, 2010;Kehrl et al, 2011;Darlington, 2015;How et al, 2017). There are two main discharge points, and the northern plume is generally more active than the southern one.…”

Section: Study Areamentioning

confidence: 99%

Effects of undercutting and sliding on calving: a global approach applied to Kronebreen, Svalbard

et al. 2018

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“…The dependence of the melting on the amount of temperature increase, indicated in Figure 8, can be fitted with a quadratic function. This is in consistence with the study of Holland et al (2008), based on idealized ice shelf geometries. The strong impact of ocean warming on the basal mass balance of EWIS results from the lack of a wide continental shelf (a type-2 ice shelf according to Beckmann and Goosse, 2003), which could protect EWIS from a warmed Antarctic Coastal Current.…”

Section: Discussionsupporting

confidence: 55%

Modelling the impact of ocean warming on melting and water masses of ice shelves in the Eastern Weddell Sea

et al. 2010

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The Eastern Weddell Ice Shelves (EWIS) are believed to modify the water masses of the coastal current and thus preconditions the water mass formation in the southern and western Weddell Sea. We apply various ocean warming scenarios to investigate the impact on the temperature-salinity distribution and the sub-ice shelf melting in the Eastern Weddell Sea. In our numerical experiments the warming is imposed homogeneously along the open inflow boundaries of the model domain, leading to a warming of the Warm Deep Water (WDW) further downstream. Our modelling results indicate a weak quadratic dependence of the melt rate at the ice shelf base on the imposed amount of warming, which is consistent with earlier studies. The total melt rate has a strong dependence on the applied ocean warming depth. If the warming is restricted to the upper ocean (above 1000 m), the water column (aside from the mixed surface layer) in the vicinity of the ice shelves stabilises. Hence, reduced vertical mixing will reduce the potential of Antarctic Bottom Water formation further downstream with consequences on the global thermohaline circulation. If the warming extends to the abyss, the WDW core moves significantly closer to the continental shelf break. This sharpens the Antarctic Slope Front and leads to a reduced density stratification. In contrast to the narrow shelf bathymetry in the EWIS region, a wider continental shelf (like in the southern Weddell Sea) partly protects ice shelves from remote ocean warming. Hence, the freshwater production rate of, e.g., the Filchner Ronne Ice Shelf increases much less compared to the EWIS for identical warming scenarios. Our study therefore indicates that the iceocean interaction has a significant impact on the temperature-salinity distribution and the water column stability in the vicinity of ice shelves located along a narrow continental shelf. The effects of ocean warming and the impact of increased freshwater fluxes on the circulation are of the same order of magnitude and superimposed. Therefore, a consideration of this interaction in large-scale climate studies is essential.

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“…A discussion of this issue has been given by Holland et al (2008). For their own idealized model they find a quadratic increase of the basal melt rate as the offshore part of the ocean outside the ice shelf warms.…”

Section: The Melting Lawmentioning

confidence: 99%

“…They report as well the relationships found in previous studies, revealing (almost) linear and (almost) quadratic laws. As Holland et al (2008) point out, 'the different modeling studies should not be intercompared'. From a limited number of experimental data an exact law cannot be detected.…”

Section: The Melting Lawmentioning

confidence: 99%

A box model of circulation and melting in ice shelf caverns

Olbers

Hellmer

2009

Ocean Dynamics

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A simple box model of the circulation into and inside the ocean cavern beneath an ice shelf is used to estimate the melt rates of Antarctic glaciers and ice shelves. The model uses simplified cavern geometries and includes a coarse parameterization of the overturning circulation and vertical mixing. The melting/freezing physics at the ice shelf/ocean interface are those usually implemented in high resolution circulation models of ice shelf caverns. The model is driven by the thermohaline inflow conditions and coupling to the heat and freshwater exchanges at the sea surface in front of the cavern. We tune the model for Pine Island Glacier and then apply it to six other major caverns. The dependence of the melting rate on thermohaline conditions at the ice shelf front is investigated for this set of caverns, including sensitivity studies, alternative parameterizations, and warming scenarios. An analytical relation between the melting rate and the inflow temperature is derived for a particular model version, showing a quadratic dependence of basal melting on a small temperature difference between the inflow and the grounding zone which changes to a linear dependence for larger differences.The model predicts melting at all ice shelf bases in agreement with observations, ranging from below a meter per year for Ronne Ice Shelf to about 25 m/y for the Pine Island Glacier. In a warming scenario with a one degree increase of the inflow temperature the latter glacier responds with a 1.4 fold increase of the melting rate. Other caverns respond by more than a ten fold increase, as e.g. Ronne Ice Shelf. The model is suitable for use as simple fast module in coarse large-scale ocean models.

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The Response of Ice Shelf Basal Melting to Variations in Ocean Temperature

Cited by 275 publications

References 48 publications

Effects of undercutting and sliding on calving: a global approach applied to Kronebreen, Svalbard

Effects of undercutting and sliding on calving: a global approach applied to Kronebreen, Svalbard

Modelling the impact of ocean warming on melting and water masses of ice shelves in the Eastern Weddell Sea

A box model of circulation and melting in ice shelf caverns

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