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The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2016-284
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
04 Jan 2017
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal The Cryosphere (TC).
Submarine melt parameterization for a Greenland glacial system model
Johanna Beckmann, Mahé Perrette, and Andrey Ganopolski Potsdam Institute for Climate Impact Research, 14412 Potsdam, Germany
Abstract. Two hundreds of marine-terminating Greenland outlet glaciers deliver more than half of the annually accumulated ice into the ocean and play an important role in the Greenland ice sheet mass loss observed since the mid 1990s. Submarine melt plays 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 and outlet glaciers will retreat, contributing to sea level rise. Projections of the future contribution of outlet glaciers to sea level rise is hampered by the necessity to use extremely high resolution of the order of a few hundred meters both for modelling of the outlet glaciers and as well as coupling them with high resolution 3D ocean models. In addition fjord bathymetry data are mostly missing or are inaccurate (errors of several 100s of meters), which questions the benefit of using computational expensive 3D models for future predictions. Here we propose an alternative approach based on using of computationally efficient parameterization of submarine melt based on turbulent plume theory. We show that such parameterization is in a reasonable agreement with several available modeling studies. We performed a suit of experiments to analyse sensitivity of these parameterizations to model parameters and climate characteristics. We found that the computationally cheap plume model demonstrates qualitatively similar behaviour as 3D gerneral circulation models. To match results of the 3D models in a quantitative manner, a scaling factor in the order of one is needed for the plume models. We applied this approach to model submarine melt for six representative Greenland glaciers and found that the parameterization 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 submarine melting of real glaciers in Greenland.

Citation: Beckmann, J., Perrette, M., and Ganopolski, A.: Submarine melt parameterization for a Greenland glacial system model, The Cryosphere Discuss., https://doi.org/10.5194/tc-2016-284, in review, 2017.
Johanna Beckmann et al.
Johanna Beckmann et al.
Johanna Beckmann et al.

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Short summary
Greenland’s glaciers that are in contact with the ocean undergo a special ice-ocean melting. To project numerically Greenland’s centennial contribution to sea level rise, it is crucial to incorporate this special melting. We demonstrate that a numerically cheap model shows the qualitative same behavior as numerical expensive 2–3 dimensional models and calculates the same melting as empirical data show. Our analytical solution gives some insight in the yet poorly understood melting behavior.
Greenland’s glaciers that are in contact with the ocean undergo a special ice-ocean melting....
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