Olivé Abelló et al., 2025 dataset - Iceberg grounding enhances the release of freshwater on the Antarctic continental shelf

The importance of Antarctic iceberg meltwater for the Southern Ocean has been a strong incentive to include Lagrangian icebergs in ocean and climate models. However, the modeled iceberg thickness has previously been constrained to 250 m, which appears to be underestimated given the frequent observations of icebergs grounded on substantially deeper bathymetric ridges. In this study, we define the initial model iceberg thickness based on the thickness of the ice shelf from which they calve and rationalize the way to define the iceberg size classes. Ocean-sea-ice-iceberg simulations indicate that more than half of the iceberg melting is discharged over the Antarctic continental shelf, reaching an average of 631 Gt yr-1 if the interaction of icebergs with bathymetry is neglected, and 802 Gt yr-1 if a simple grounding scheme is implemented. Such additional freshwater injected into regions prone to sea ice production has important consequences for the ocean properties around Antarctica. This freshwater enhances the ocean stratification, limiting deep convection and favoring the intrusion of relatively warm Circumpolar Deep Water onto some parts of the continental shelf. Moreover, the simulated distribution of grounded icebergs blocks drifting sea ice, thereby promoting areas of thick sea ice and polynyas when the fast ice parameterization is included. 

The output datasets for the simulations performed in Anna Olivé Abelló, Pierre Mathiot, Nicolas C Jourdain, et al. Iceberg grounding enhances the release of freshwater on the Antarctic continental shelf. Authorea. May 27, 2025. Preprint. DOI: 10.22541/au.174838305.51204729/v1 are available here to improve the iceberg thickness distribution and to rationalize the way to define the iceberg size classes. The code developed in the NEMO iceberg module is going to be publicly available at the GitLab repository: https://forge.nemo-ocean.eu/.

The output netCDF files from the REF experiment include:

• Grounded_Icebergmask.nc: Grounded icebergs masks (frequency mask (between 0 and 1) and binary mask (0 or 1), where 1 indicates at least one grounding event over 25 years).
• Iceberg_MaxMeanThickness_annual25y.nc: Annual climatology (25 years) of mean and maximum iceberg thickness dataset, including also mean thicknesses per IMBIE basin.
• Iceberg_MaxMeanThickness_month25y.nc: Monthly climatology (25 years) of mean and maximum iceberg thickness dataset, including also mean thicknesses per IMBIE basin.
• Iceberg_Melt_annual25y.nc: Annual climatology (25 years) of iceberg melt rates dataset, including also normalized melt rates and per IMBIE basin.
• Iceberg_Melt_month25y.nc: Monthly climatology (25 years) of iceberg melt rates dataset, including also normalized melt rates and per IMBIE basin.

Additionally, we attach the calving rates, Antarctica ice-shelf thickness along the calving front and IMBIE basin IDs (calving_Antarctic_coast.nc, Antarctic_iceshelf_thickness_coast.nc and IMBIEbasin_coast.nc, respectively). Please read the README.rt file for further details.

This research was supported by Ocean Cryosphere Exchanges in ANtarctica: Impacts on Climate and the Earth system, OCEAN ICE, which is funded by the European Union, Horizon Europe Funding Programme for research and innovation under grant agreement Nr. 101060452, 10.3030/101060452. OCEAN ICE contribution number 24. This work was funded by UK Research and Innovation (UKRI) under the UK government’s Horizon Europe funding Guarantee, grant number 10048443. Moreover, this study has received funding from Agence Nationale de la Recherche - France 2030 as part of the PEPR TRACCS programme under grant numbers ANR-22-EXTR-0008 (IMPRESSION-ESM) and ANR-22-EXTR-0010 (ISClim). This work was granted access to the high-performance computing (HPC) resources of TGCC under allocation A0140106035 attributed by GENCI.