Data from: Using Antarctic subglacial relic landscapes to inform past ice sheet retreat in the warm Pliocene
Data files
Jan 05, 2026 version files 4.20 GB
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Code.zip
10.33 KB
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ISM_Output_Rae_All.zip
4.06 GB
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ISM_Output_Timeseries_Rae.zip
136.75 MB
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README.md
4.45 KB
Abstract
We use high-resolution ice sheet model simulations to better understand if the preservation of a relic landscape precludes significant glacial retreat into the Aurora Subglacial Basin sector of East Antarctica in at least the past 3 million years. Transient ice sheet model (ISM) simulations were performed through selected glacial-interglacial cycles of the mid-Piacenzian warm period (mPWP). We use the PSU-ISM, a 3-D thermomechanical ice sheet-shelf model, with climatic forcing applied using the multi-dimensional matrix method. To ensure stability of the high-resolution runs, a sequence of simulations at increasing spatial and temporal resolution was required. To explore the relationship between retreat in this sector and the preserved landscape, an ensemble of simulations was created by invoking the Marine Ice Cliff Instability (MICI) process at a range of levels. Continental scale simulations at 40 km resolution were run for 500 kyrs (3.4–2.9 Ma) to identify time periods of greatest retreat for each calving parameter set. We focused on four interglacial periods for the highest resolution (5 km) simulations, which relate to the Marine Isotope Stages (MIS): MG1, KM5, K1, G17. To understand controls on the preservation of the Highland A relic landscape, we present key model variables relating to the basal thermal regime and erosional potential.
Dataset DOI: 10.5061/dryad.4b8gthtsv
Description of the data and file structure
This dataset contains time-evolving Antarctic ice sheet model (ISM) output relating to multiple de-glaciation cycles within the Pliocene. To conduct these transient simulations, we use the PSU-ISM.
Files and variables
File: ISM_Output_Timeseries_Rae.zip
Description:
Tabular data (can be opened with any text editor) relating to the continental-scale model simulations ('Rae' forcing), performed at 40 km grid resolution. Model history writes occur every 1000 years (from 3.4 - 2.9 Ma). Five simulation files relate to different levels of Marine Ice Cliff Instability (MICI), which is parameterised in the model. The levels are: Off, Low, MedLo, MedHi, and Max.
Key tabular fields include:
- 'esl': ice sheet configuration converted to sea level equivalent (m)
- 'esle': ice sheet configuration converted to sea level equivalent for East Antarctica only (m)
- Time and run identifiers
- time – Model time (years relative to present; negative values indicate years before present).
- weirun – Model run identifier or weighting factor (constant in this output).
- Orbital and astronomical parameters
- ro18 – δ¹⁸O reference value or isotopic forcing parameter.
- sealev – Global mean sea level relative to present (m).
- ecc – Orbital eccentricity.
- obl – Orbital obliquity (tilt; degrees).
- prec – Climatic precession parameter.
- dtanta – Antarctic temperature anomaly (°C).
- dtants – Antarctic summer temperature anomaly (°C).
- dtantj – Antarctic winter temperature anomaly (°C).
- dtseas – Seasonal temperature anomaly (°C).
- rco2 – Atmospheric CO₂ concentration or radiative forcing related to CO₂.
- facice – Ice-related forcing factor.
- facorb – Orbital forcing factor.
- facco2 – CO₂ forcing factor.
- Ice volume (km³)
- toti – Total ice volume.
- totig – Grounded ice volume.
- totif – Floating ice volume.
- Ice area (km²)
- tota – Total ice area.
- totag – Grounded ice area.
- totaf – Floating ice area.
- Sea-level and height contributions (m)
- h – Mean ice thickness or equivalent height.
- eofe – East Antarctic ice contribution to sea level.
- eofw – West Antarctic ice contribution to sea level.
- eof – Total Antarctic ice contribution to sea level.
- esle – East Antarctic sea-level equivalent.
- eslw – West Antarctic sea-level equivalent.
- esl – Total sea-level equivalent from ice.
- odtsurf – Ocean surface temperature anomaly (°C).
- odt400 – Ocean temperature anomaly at 400 m depth (°C).
File: ISM_Output_Rae_All.zip
Description:
NetCDF files (.nc) from each simulation ('Rae' forcing) were produced for the Aurora Subglacial Basin domain over 4 interglacial periods, which related to the Marine Isotope Stages (MIS): MG1, KM5, K1, G17. These simulations have a duration of 25 kyr with model history writes every 100 years. The spatial resolution is 5 km. As above, there are different simulations for the five levels of Marine Ice Cliff Instability (MICI): Off, Low, MedLo, MedHi, and Max. 20 files in total cover 4 MIS for 5 MICI levels.
Key 3D model output fields include:
- 'h': ice thickness (m)
- 'maskwater': 0 if bare ground or grounded ice; 1 if ocean (with or without ice shelf)
- 'budgall': annual overall local ice budget (m y-1 ice equiv.)
- 'fract': basal non-frozen fraction
- 'heatb': heating due to basal shear stress (J m-2 y-1)
- 'ua' & 'va': vertical-mean horizontal ice velocities (m y-1)
- 'ubot' & 'vbot': basal ice horizontal velocities (m y-1)
Code/software
File: Code.zip
Results_Metrics.py:
This Python script file conducts the majority of analyses used in the manuscript, and can be used with the ISM_Output_Rae_All.zip data files.
Plotting_model_output_timeseries.py
This Python script file can be used to analyse the tabular output from the continental-scale model simulations contained in the ISM_Output_Timeseries_Rae.zip folder.
For both scripts, the user will need to install the Python libraries listed at the top of the file and set up the directories ('dir_path') to reference the location where the data (already unzipped) has been downloaded to.