Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2017-58
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
20 Apr 2017
Review status
This discussion paper is under review for the journal The Cryosphere (TC).
Modelling present-day basal melt rates for Antarctic ice shelves using a parametrization of buoyant meltwater plumes
Werner M. J. Lazeroms1, Adrian Jenkins2, G. Hilmar Gudmundsson2, and Roderik S. W. van de Wal1 1Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands
2British Antarctic Survey, Natural Environment Research Council, Cambridge, United Kingdom
Abstract. Basal melting below ice shelves is a major factor in the decline of the Antarctic ice sheet, which can contribute significantly to possible future sea-level rise. Therefore, it is important to have an adequate description of the basal melt rates for use in ice-dynamical models. Most current ice models use rather simple parametrizations based on the local balance of heat between ice and ocean. In this work, however, we use a recently derived parametrization of the melt rates based on a buoyant meltwater plume travelling upward beneath an ice shelf. This plume parametrization combines a nonlinear ocean temperature sensitivity with an inherent geometry dependence, which is mainly described by the grounding-line depth zgl and the local slope α of the ice-shelf base. For the first time, this type of parametrization is evaluated on a two-dimensional grid covering the entire Antarctic continent. In order to apply the essentially one-dimensional parametrization to realistic ice-shelf geometries, we present an algorithm that determines effective values for zgl and α for any point beneath an ice shelf. Furthermore, since detailed knowledge of temperatures and flow patterns in the ice-shelf cavities is sparse or absent, we construct an effective ocean temperature field from observational data with the purpose of matching (area-averaged) melt rates from the model with observed present-day melt rates. The result is a realistic map of basal melt rates around Antarctica, not only in terms of average values, but also in terms of the spatial pattern, with high melt rates typically occurring near the grounding line. The plume parametrization and the effective temperature field are therefore promising tools for future simulations of the Antarctic ice sheet.

Citation: Lazeroms, W. M. J., Jenkins, A., Gudmundsson, G. H., and van de Wal, R. S. W.: Modelling present-day basal melt rates for Antarctic ice shelves using a parametrization of buoyant meltwater plumes, The Cryosphere Discuss., doi:10.5194/tc-2017-58, in review, 2017.
Werner M. J. Lazeroms et al.
Werner M. J. Lazeroms et al.
Werner M. J. Lazeroms et al.

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Short summary
Basal melting of ice shelves is a major factor in the decline of the Antarctic ice sheet, which can contribute significantly to sea-level rise. Here, we investigate a new basal-melt model based on the dynamics of meltwater plumes. For the first time, this model is applied to all Antarctic ice shelves. The model results in a realistic melt-rate pattern given suitable data for the topography and ocean temperature, making it a promising tool for future simulations of the Antarctic ice sheet.
Basal melting of ice shelves is a major factor in the decline of the Antarctic ice sheet, which...
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