Preprints
https://doi.org/10.48550/arXiv.2507.22485
https://doi.org/10.48550/arXiv.2507.22485
28 Aug 2025
 | 28 Aug 2025

Physics-constrained generative machine learning-based high-resolution downscaling of Greenland's surface mass balance and surface temperature

Nils Bochow, Philipp Hess, and Alexander Robinson

Abstract. Accurate, high-resolution projections of the Greenland ice sheet’s surface mass balance (SMB) and surface temperature are essential for understanding future sea-level rise, yet current approaches are either computationally demanding or limited to coarse spatial scales. Here, we introduce a novel physics-constrained generative modeling framework based on a consistency model (CM) to downscale low-resolution SMB and surface temperature fields by a factor of up to 32 (from 160 km to 5 km grid spacing) in a few sampling steps. The CM is trained on monthly outputs of the regional climate model MARv3.12 and conditioned on ice-sheet topography and insolation. By enforcing a hard conservation constraint during inference, we ensure approximate preservation of SMB and temperature sums on the coarse spatial scale as well as robust generalization to extreme climate states without retraining. On the test set, our constrained CM achieves a continued ranked probability score of 6.31 mmWE for the SMB and 0.1 K for the surface temperature, outperforming interpolation-based downscaling. Together with spatial power-spectral analysis, we demonstrate that the CM faithfully reproduces variability across spatial scales. We further apply bias-corrected outputs of the NorESM2 Earth System Model as inputs to our CM, to demonstrate the potential of our model to directly downscale ESM fields. Our approach delivers realistic, high-resolution climate forcing for ice-sheet simulations with fast inference and can be readily integrated into Earth-system and ice-sheet model workflows to improve projections of the future contribution to sea-level rise from Greenland and potentially other ice sheets and glaciers too.

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Journal article(s) based on this preprint

30 Mar 2026
Physics-constrained generative machine learning-based high-resolution downscaling of Greenland's surface mass balance and surface temperature
Nils Bochow, Philipp Hess, and Alexander Robinson
The Cryosphere, 20, 1841–1866, https://doi.org/10.5194/tc-20-1841-2026,https://doi.org/10.5194/tc-20-1841-2026, 2026
Short summary
Nils Bochow, Philipp Hess, and Alexander Robinson

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-3927', Anonymous Referee #1, 08 Oct 2025
  • RC2: 'Comment on egusphere-2025-3927', Anonymous Referee #2, 17 Oct 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-3927', Anonymous Referee #1, 08 Oct 2025
  • RC2: 'Comment on egusphere-2025-3927', Anonymous Referee #2, 17 Oct 2025

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
ED: Publish subject to revisions (further review by editor and referees) (01 Dec 2025) by Ruth Mottram
AR by Nils Bochow on behalf of the Authors (14 Jan 2026)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to revisions (further review by editor and referees) (10 Feb 2026) by Ruth Mottram
AR by Nils Bochow on behalf of the Authors (11 Feb 2026)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (03 Mar 2026) by Ruth Mottram
AR by Nils Bochow on behalf of the Authors (12 Mar 2026)  Manuscript 

Journal article(s) based on this preprint

30 Mar 2026
Physics-constrained generative machine learning-based high-resolution downscaling of Greenland's surface mass balance and surface temperature
Nils Bochow, Philipp Hess, and Alexander Robinson
The Cryosphere, 20, 1841–1866, https://doi.org/10.5194/tc-20-1841-2026,https://doi.org/10.5194/tc-20-1841-2026, 2026
Short summary
Nils Bochow, Philipp Hess, and Alexander Robinson
Nils Bochow, Philipp Hess, and Alexander Robinson

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Short summary
This study presents a fast, physics-guided machine-learning method that downscales coarse climate fields to fine resolution while enforcing conservation of large-scale totals. Trained on regional climate simulations and driven by Earth system model output, it handles extremes and outperforms linear interpolation, providing realistic, high-resolution forcing for ice-sheet models and improving projections of Greenland’s sea-level contribution.
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