Abstract
Abstract. Future sea-level change projections with process-based stand-alone 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 geometry used by the climate model. We present a method for applying 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 climate model geometry directly to a large range of modelled ice sheet model geometries.
Highlights
Process-based ice sheet model projections are an important tool for estimating future sea-level change in the context of the Intergovernmental Panel on Climate Change assessment cycle (IPCC, 2013)
In this work we address the problems arising from a mismatch of the modelled ice sheet geometry with the geometry used by the climate model
The aSMB error integrated over all basins is 18 km3 yr−1 (Fig. 6) compared to an ensemble range (650 km3 yr−1) and ensemble standard deviation (240 km3 yr−1) for the six CMIP5 models used in Intercomparison Project for CMIP6 (ISMIP6) (Goelzer et al, 2020)
Summary
Process-based ice sheet model projections are an important tool for estimating future sea-level change in the context of the Intergovernmental Panel on Climate Change assessment cycle (IPCC, 2013). Problems were identified when a given surface mass balance anomaly (aSMB) was applied to the wide range of Greenland ice sheet models used in the community (Goelzer et al, 2018). Ice sheet models with larger-thanobserved initial areas exhibit larger melting under such forcing because their ablation areas are extended outwards To address this problem, we present here a method for remapping the SMB anomaly as a function of surface elevation and thereby produce physically consistent forcing for different ice sheet model geometries. The proposed method was developed for future sea-level change projections made with a large ensemble of ice sheet models (with possibly widely differing initial geometries) forced by output of different climate models and scenarios. In the following we describe our approach and method (Sect. 2), the resulting forcing (Sect. 3), and time-dependent applications (Sect. 4) and discuss the results (Sect. 5)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
