Iceberg melting substantially modifies oceanic heat flux towards a major Greenlandic tidewater glacier

Davison, Benjamin; Cowton, Tom; Cottier, Finlo; Sole, Andrew

doi:10.1038/s41467-020-19805-7

Cited by 37 publications

(65 citation statements)

References 80 publications

(190 reference statements)

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“…Submarine iceberg melting is simulated using the 'IceBerg' package within MITgcm (Davison et al, 2020), with an ice temperature of -10°C (Inall et al, 2014;Luthi et al, 2002;Sciascia et al, 2013;Sutherland and Straneo, 2012). This package uses the velocity-dependent three-equation melt rate parameterisation (Holland and Jenkins, 1999;Xu et al, 2012) to resolve the vertical pattern of submarine melting of individual icebergs.…”

Section: Iceberg-ocean Interactionmentioning

confidence: 99%

“…Melt-driven plumes are not simulated directly; instead, their effect on melt rates is parameterised by applying a minimum face-normal current speed of 0.06 m s -1 to each iceberg face. This minimum current speed is based on line plume modelling (Davison et al, 2020). The package does not include the effect of waves or mechanical iceberg breakup; therefore, melt rates calculated here are conservative.…”

Section: Iceberg-ocean Interactionmentioning

confidence: 99%

“…The package does not include the effect of waves or mechanical iceberg breakup; therefore, melt rates calculated here are conservative. We use standard parameter values (Cowton et al, 2015;Davison et al, 2020;Jackson et al, 2020) for the drag coefficient (0.0025), and thermal and salt turbulent transfer coefficients (0.022 and 0.00062, respectively). The icebergs are rectangular in plan-view and have flat, vertical sides.…”

Section: Iceberg-ocean Interactionmentioning

confidence: 99%

“…However, there remain substantial differences between modelled water properties and those that are observed adjacent to tidewater glaciers (Cowton et al, 2016;Davison et al, 2020;Fraser and Inall, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…CC BY 4.0 License. associated with submarine iceberg melting increases greatly the model's ability to reproduce observed glacier-adjacent water properties (Davison et al, 2020). However, iceberg concentration, keel depth, and size-frequency distribution likely vary hugely between fjords as well as over time, though observations of icebergs at the fjord scale are sparse (Enderlin et al, 2016;Moyer et al, 2019;Rezvanbehbahani et al, 2020;Sulak et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Modelling the effect of submarine iceberg melting on glacier-adjacent water properties

Davison

Cowton

Sole

et al. 2021

Preprint

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Abstract. The rate of ocean-driven retreat of Greenland’s tidewater glaciers remains highly uncertain in predictions of future sea level rise, in part due to poorly constrained glacier-adjacent water properties. Icebergs and their meltwater contributions are likely important modifiers of fjord water properties, yet their effect is poorly understood. Here, we use a 3-D ocean circulation model, coupled to a submarine iceberg melt module, to investigate the effect of submarine iceberg melting on glacier-adjacent water properties in a range of idealised settings. Submarine iceberg melting can modify glacier-adjacent water properties in three principle ways: (1) substantial cooling and modest freshening in the upper ~50 m of the water column; (2) warming of Polar Water at intermediate depths due to iceberg melt-induced upwelling of warm Atlantic Water, and; (3) warming of the deeper Atlantic Water layer when vertical temperature gradients through this layer are steep (due to vertical mixing of warm water at depth), but cooling of the Atlantic Water layer when vertical temperature gradients are shallow. The overall effect of iceberg melt is to make glacier-adjacent water properties more uniform with depth. When icebergs extend to, or below, the depth of a sill at the fjord mouth, they can cause cooling throughout the entire water column. All of these effects are more pronounced in fjords with higher iceberg concentrations and deeper iceberg keel depths. These iceberg melt-induced changes to glacier-adjacent water properties will reduce rates of glacier submarine melting near the surface, but increase them in the Polar Water layer, and cause typically modest impacts in the Atlantic Water layer. These results characterise the important role of submarine iceberg melting in modifying ice sheet-ocean interaction, and highlight the need to improve representations of fjord processes in ice sheet-scale models.

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