Simulation data supporting: Ocean carbon sequestration during glacial climates due to combined Antarctic sea ice expansion and ocean circulation change
Data files
Sep 08, 2026 version files 554.33 MB
-
MITgcm_Input_Files.zip
283.45 KB
-
MITgcm_Simulations.zip
553.75 MB
-
MITgcm_Source_Code.zip
281.61 KB
-
README.md
7.99 KB
Sep 16, 2026 version files 554.33 MB
-
MITgcm_Input_Files.zip
284.55 KB
-
MITgcm_Simulations.zip
553.75 MB
-
MITgcm_Source_Code.zip
281.61 KB
-
README.md
7.99 KB
Abstract
Glacial-interglacial transitions punctuate Earth's Quaternary climate, accompanied by significant atmospheric CO₂ and ocean carbon storage changes. The cause of atmospheric carbon drawdown during glaciations is uncertain, involving many mechanisms whose interactions are poorly understood. Here, we show that the combined expansion of Antarctic sea ice and associated changes in the meridional overturning efficiently sequester carbon in the ocean abyss, leading to a decline in atmospheric CO₂. In contrast, changes in sea ice and circulation individually result in ocean CO₂ outgassing. When sea ice expansion and circulation changes act together, they enhance biological carbon storage by reducing ocean–atmosphere fluxes in the Southern Ocean, without invoking external drivers of the biological pump. This reduction inhibits the outgassing of upwelled remineralized carbon and promotes its resubduction into the abyss. Together, these results reveal a reinforcing feedback linking atmospheric cooling, Antarctic sea ice expansion, and ocean circulation changes to enhanced biological carbon storage and atmospheric CO₂ drawdown. This repository contains the MITgcm simulation outputs, modified source code and model input files used in this study.
Dataset DOI: 10.5061/dryad.6wwpzgncr
Description of the data
This repository contains MITgcm simulation outputs, modified source code, and model input files associated with the study:
“Ocean Carbon Sequestration During Glacial Climates Due to Combined Antarctic Sea Ice Expansion and Ocean Circulation Change”
The dataset includes ocean physical and biogeochemical diagnostics from a suite of idealized interglacial and glacial simulations used to investigate the individual and combined effects of Antarctic sea ice expansion, seawater cooling, and ocean circulation changes on ocean carbon storage and atmospheric CO₂.
Files and variables
Files:
MITgcm_Simulations.zip
MITgcm simulation outputs for all experiments.
MITgcm_Source_Code.zip
Modified MITgcm source code used to generate the simulations.
MITgcm_Input_Files.zip
MITgcm runtime parameter files and scripts used to generate the model forcing fields and configure the simulations.
MITgcm_Simulations.zip structure
Grid and wind directories
grid/
Contains the model grid used for all simulations.
wind/
Contains the 10-m wind-speed field used to compute gas equilibration timescales, τgas, used in Figure 4 of the manuscript.
Simulation directories
Each top-level directory corresponds to one simulation.
Examples include:
Interglacial_ReferenceGlacial_ReferenceGlacial_SeaIceGlacial_CirculationGlacial_SeaIce_CirculationGlacial_Temperature- etc.
Each simulation directory contains two subdirectories:
Physics/Physics_and_Biogeochemistry/
Physics_and_Biogeochemistry
Contains outputs from the fully coupled physical-biogeochemical simulations.
Main files include:
oceDiag.nc
Contains 3D ocean physical diagnostics:
THETA: potential temperatureSALT: salinityUVELMASS: zonal mass-weighted velocityVVELMASS: meridional mass-weighted velocity
GM_PsiY: Gent–McWilliams bolus transport streamfunction
This file is not included for the "driver" simulations: Glacial_SeaIce, Glacial_Temperature, Glacial_Circulation, Glacial_SeaIce_Circulation, Glacial_SeaIce_Temperature and Glacial_Circulation_Temperature.
iceDiag.nc
Contains sea-ice diagnostics:
SIarea: fractional sea-ice-covered area
This file is not included for the "driver" simulations.
surfDiag.nc
Contains surface diagnostics:
DICATCO2: atmospheric pCO₂DICATCAR: atmospheric carbon inventoryETAN: sea surface height anomalyMXLDEPTH: mixed-layer depth
For the "driver" simulations, only:
DICATCO2DICATCAR
are included in surfDiag.nc.
dicDiag.nc
Contains 3D biogeochemical tracers:
- dissolved inorganic carbon
- alkalinity
- phosphate
- dissolved oxygen
- dissolved organic phosphorus
- preformed carbon
- preformed alkalinity
- preformed phosphate
- preformed oxygen
- age tracers
The age tracers correspond to restoring timescales representative of different air–sea equilibration rates.
Physics
Contains outputs from simulations without biological activity. These simulations are used to diagnose physical and biological disequilibrium carbon storage.
Files include:
dicDiag.ncsurfDiag.nc
These files contain the abiotic equivalents of the corresponding tracers and surface carbon diagnostics.
MITgcm_Source_Code.zip structure
The archive contains modified MITgcm source files grouped into three simulation families:
Reference_and_All_Atmospheric_Cooling/: modified source files used to compile the MITgcm configurations forInterglacial_Reference,Glacial_Reference,Glacial_minus_0.5deg,Glacial_minus_1deg,Glacial_minus_2deg, andGlacial_minus_9deg.Driver_Simulations/: modified source files used to compile the MITgcm configurations forGlacial_SeaIce,Glacial_Temperature,Glacial_Circulation,Glacial_SeaIce_Circulation,Glacial_SeaIce_Temperature, andGlacial_Circulation_Temperature.Permeable_Sea_Ice/: modified source files used to compile the MITgcm configurations forInterglacial_Permeable_SeaIceandGlacial_Permeable_SeaIce.
Each simulation-family directory contains the same set of source and configuration files, with modifications specific to that simulation family:
code/: modified MITgcm core and physical-package source and configuration files.
bgc/: modified MITgcm biogeochemical and carbon-cycle source and configuration files.
The code/ directory contains:
CPP_OPTIONS.h, DIAGNOSTICS_SIZE.h, EXF_OPTIONS.h, PTRACERS_SIZE.h, SEAICE_OPTIONS.h, SIZE.h, packages.conf, exf_bulkformulae.F, exf_getforcing.F, ptracers_apply_forcing.F, ptracers_forcing_surf.F, and seaice_solve4temp.F.
The bgc/ directory contains:
DIC_ATMOS.h, DIC_LOAD.h, DIC_OPTIONS.h, DIC_VARS.h, GCHEM_OPTIONS.h, bio_export.F, calcite_saturation.F, carbon_chem.F, dic_atmos.F, dic_biotic_forcing.F, dic_diagnostics_init.F, dic_fields_load.F, dic_fields_update.F, dic_ini_atmos.F, dic_ini_forcing.F, dic_init_fixed.F, dic_read_co2_pickup.F, dic_readparms.F, dic_surfforcing.F, dic_surfforcing_init.F, dic_write_pickup.F, fe_chem.F, gchem_forcing_sep.F, gchem_preformed_tracers.F, and o2_surfforcing.F.
The code/ and bgc/ directories corresponding to the appropriate simulation family should be supplied to genmake2 when building MITgcm.
For example, a build/ directory can be created alongside the corresponding code/ and bgc/ directories. From within the build/ directory, the model can be configured and compiled using commands such as:
/PATH/TO/MITGCM/tools/genmake2 -mods='../code ../bgc' -mpi -optfile=/PATH/TO/OPTFILE
make depend
make
The compiler options and paths should be adapted to the user's computing environment.
Instructions for obtaining and compiling MITgcm are provided in the MITgcm documentation:
https://mitgcm.readthedocs.io/en/latest/getting_started/getting_started.html
MITgcm_Input_Files.zip structure
The archive contains the MITgcm runtime parameter files and forcing-generation scripts used to configure the simulations.
Input
Contains the MITgcm runtime parameter files: data, data.cal, data.diagnostics, data.dic, data.exf, datagchem, data.gmredi, data.mnc, data.pkg, data.ptracers, data.seaice, eedata, and eedata.mth.
Most files are common to all experiments. Differences among experiments are documented in README.txt.
Forcing
Contains scripts and supporting files used to generate the model forcing fields:
genforcing.m
Generates the idealized bathymetry and atmospheric forcing fields: topo.bin, taux.bin, tauy.bin, Tatm.bin, lwdown.bin, precip.bin, evap.bin, and runoff.bin.
genSIL.m
Generates the silicate forcing field: sili.bin.
grid.nc
Model grid used to generate forcing fields.
sillev1.bin
Source silicate climatology used by genSIL.m.
README.txt
Documents the experiment-specific differences in model configuration, including time-stepping parameters, biological activity settings, driver simulations, and forcing generation.
Code/software
All simulation outputs are provided in NetCDF format and can be viewed using standard NetCDF-compatible software and libraries.
The files can be analyzed using a wide range of open-source tools supporting the NetCDF format, including Python and MATLAB.
No proprietary software is required to access or analyze the data.
Access information
The simulations were performed using the MITgcm ocean circulation model (MITgcm), which is publicly available from: https://mitgcm.org/
Changes after Sep 8, 2026: Corrected a diagnostic stream identifier (1 changed to 4 for the fourth diagnostic output stream) in the Input/data.diagnostics file within MITgcm_Input_Files.zip.
