Remapping of Greenland ice sheet surface mass balance anomalies for large ensemble sea-level change projections

• Main Authors: Goelzer, Heiko, Noel, Brice P. Y., Edwards, Tamsin L., Fettweis, Xavier, Gregory, Jonathan M., Lipscomb, William H., Wal, Roderik S. W., Broeke, Michiel R.
• Format: Text
• Language: English
• Published: 2019
• Subjects: Greenland; Ice Sheet
• Online Access: https://doi.org/10.5194/tc-2019-188; https://www.the-cryosphere-discuss.net/tc-2019-188/

Future sea-level change projections with process-based standalone ice sheet models are typically driven with surface mass balance (SMB) forcing derived from climate models. In this work we address the problems arising from a mismatch of the modelled ice sheet geometry with the one used by the climate model. We present a method to apply SMB forcing from climate models to a wide range of Greenland ice sheet models with varying and temporally evolving geometries. In order to achieve that, we translate a given SMB anomaly field as a function of absolute location, to a function of surface elevation for 25 regional drainage basins, which can then be applied to different modelled ice sheet geometries. The key feature of the approach is the non-locality of this remapping process. The method reproduces the original forcing data closely when remapped to the original geometry. When remapped to different modelled geometries it produces a physically meaningful forcing with smooth and continuous SMB anomalies across basin divides. The method considerably reduces non-physical biases that would arise by applying the SMB anomaly derived for the observed geometry directly to a large range of modelled ice sheet model geometries.