Geodetic observations in West Antarctica reveal geodynamically consistent 3-d mantle viscosity
Data files
Sep 10, 2026 version files 2.59 GB
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dePolo_etal_input.tar.gz
2.28 GB
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dePolo_etal_v6_output.tar.gz
311.09 MB
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README.md
10.06 KB
Abstract
The rapid ice loss in West Antarctica since the 1990s has led to significant ice surface lowering, regional bedrock uplift, and gravity reduction, as measured by geodetic observations. The bedrock (crustal) motions and gravity changes result from glacial isostatic adjustment (GIA), a process controlled by Earth’s viscoelastic properties and deglaciation history. In this study, we present GIA models with geodynamically consistent three-dimensional mantle viscoelastic structures and reconstructed ice history for Antarctica from 1900 to 2020, which explain both the observed GNSS crustal motions and GRACE gravity changes in West Antarctica. Our study demonstrates that a mantle rheology including a weak asthenosphere and temperature-dependent viscosity is consistent with both mantle convection at million-year timescales and ongoing decadal GIA occurring in West Antarctica.
Dataset DOI: 10.5061/dryad.5hqbzkhms
Description of the data and file structure
These files include the input files required for select cases associated with dePolo et al. 2026 and the output files of preferred case V6. These input files are for 3-D glacial isostatic adjustment forward models performed with CitcomSVE-3.0, which require input of an ice history model and solid Earth structure. The four ice history models (WAICE-A, -B, -C, and -D) are included as CitcomSVE3.0 input files. The 3-D mantle viscosity files are also included in the CitcomSVE-3.0 input file format. The 3-D mantle viscosity structures (i.e., 3Dvisc_WA1D_VE300.dat, etc.) include the effective activation energy in the model name. Thus, '3Dvisc_WA1D_VE300.dat' has an effective activation energy of 300 kJ/mol. These output files include the spherical harmonic expansions of radial displacements and gravitational potential anomalies, as well as incremental surface displacements on a regular grid.
File structure for the zipped file: dePolo_etal_input.tar.gz
$cd dePolo_etal_input/models_and_inputs
This directory includes the necessary ice history models, 3-D viscosity models, and GIA input files for cases V1, V6, V15, V20, V23, V1_1D, and V2_1D.
$cd dePolo_etal_input/full_coord_of_cap.c
This file includes the necessary subroutine for the mesh refinement of CitcomSVE-3.0
Files and variables
File: /dePolo_etal_inputs/full_coord_of_cap.c
Description: This subroutine is required to refine the CitcomSVE-3.0 mesh grid for higher horizontal resolution (numerical) in West Antarctica. To implement, CitcomSVE-3.0 must be first downloaded from Github (https://github.com/shjzhong/CitcomSVE/tree/CitcomSVE-3.0). The full_coord_of_cap subroutine found in ‘Full_sphere_related.c’ (lines 155 - 522) must be replaced by the subroutine in this file of the same name. The code must then be compiled with $make CitcomSVE.x . Then the user will be able to achieve the same numerical resolution as our study.
Directory: dePolo_etal_inputs/models_and_inputs
Description: input files for select model cases in dePolo et al. 2026.
Directory: /dePolo_etal_inputs/models_and_inputs/icehistory_waice_A
I will first describe the files within icehistory_waice_A; then the structure is identical for waice_B, waice_C, and waice_D.
File: ./icehistory_waice_A/ice6g_0p1ka_stages_timeA.dat
Description: This file determines the numerical time step for the model run. The first line is the number of stages (16) and the unit of time (1 - units are in 1000 of years, or ka). This ice history model spans 120 years prior to 2020, divided into 16 stages. In the second line, the number represents the start time of the model (i.e., -0.120) is 120 years before 2020, i.e., the year 1900. The second number specifies the number of numerical time steps used to cover this stage (i.e., 20). Therefore, there is model output every 4 years from 1900 - 1980. The third line, -0.040, is the start of the second stage and the end of the first stage. The total number of time steps for these models is 51.
File: ./icehistory_waice_A/ice6g.*
Description: WAICE-A ice history model described in dePolo etal., 2026. The first line is the number of grid cells in longitude and latitude (i.e., the resolution, 3600 and 1800 for a 0.1° by 0.1° grid). The numbering starts at the North Pole region and increases in longitude at a fixed latitude, before continuing to the next latitude. Continuing until it reaches the South Pole region. The following lines are structured as: 1st column - longitude; 2nd column - latitude; 3rd column - ice height. The star in the file name is replaced by a number (0 to 16), reflecting the stage number consistent with the time file.
File: ./icehistory_waice_A/ocn6g.*
Description: This is the ocean function file for every stage of the ice distribution file. This file describes the distribution of the oceans and continents on the same regular grid as the ice files. The 3rd column is 1 (true) for ocean regions and 0 (false) for land regions.
File: ./3Dvisc_WA1D_VE300.dat
I will describe the file structure for an activation energy of 300 kJ/mol, and this structure is identical for the remaining 3Dvisc files.
Description: The structure of this file is described in the first 2 lines. The file has 89 radial layers and is on a 0.5° by 0.5° grid. The set of lines (3 to 92) lists the depths of the viscosity model from the bottommost layer to the topmost layer. Lines 93 to 813 list the longitudes of the viscosity grid, from 0.25° to 359.75° with an increment of 0.5°. Lines 814 to 1174 list the latitudes of the viscosity grid, from 89.75° to -89.75° with an increment of 0.5°. The remaining segments detail the 3D viscosity at each depth of the 0.5° by 0.5° grid, starting from the bottommost layer to the topmost layer. The viscosity is given in Pa s. For each layer, there should be 720 × 360 = 259,200 grid points. The ordering of the grid points is similar to the ice model, starting at the North Pole, such that (0.25°, 89.75° N), . . ., (359.75°, 89°N), . . ., (0.25°, 89.25°N), . . ., (359.75°, 89.75°S).
File: ./model.barletta_visc
Description: This is the 1D viscosity profile, adapted from Barletta et al., 2018, as the CitcomSVE-3.0 input used for reference in our study.
File: ./model.vm5a
Description: This is the 1D viscosity profile, adapted from Peltier et al., 2015, as the CitcomSVE-3.0 input used for reference in our study.
File: input_dePolo_etal_v1
Description: CitcomSVE-3.0 (GIA forward model) input file which requires '3Dvisc_WA1D_VE0.dat' and 'icehistory_waice_A'.
File: input_dePolo_etal_v6
Description: CitcomSVE-3.0 (GIA forward model) input file which requires '3Dvisc_WA1D_VE300.dat' and 'icehistory_waice_A'.
File: input_dePolo_etal_v15
Description: CitcomSVE-3.0 (GIA forward model) input file which requires '3Dvisc_WA1D_VE250.dat' and 'icehistory_waice_B'.
File: input_dePolo_etal_v20
Description: CitcomSVE-3.0 (GIA forward model) input file which requires '3Dvisc_WA1D_VE300.dat' and 'icehistory_waice_C'.
File: input_dePolo_etal_v23
Description: CitcomSVE-3.0 (GIA forward model) input file which requires '3Dvisc_WA1D_VE250.dat' and 'icehistory_waice_D'.
File: input_dePolo_etal_v1_1D
Description: CitcomSVE-3.0 (1D GIA forward model) input file which requires 'model.vm5a' and 'icehistory_waice_A'.
File: input_dePolo_etal_v2_1D
Description: CitcomSVE-3.0 (1D GIA forward model) input file which requires 'model.vm5a' and 'icehistory_waice_A'.
File structure for zipped file: dePolo_etal_v6_output.tar.gz
$cd dePolo_etal_v6_output/incr_disp
This directory includes the incremental surface displacement output from the model run between the time steps 31-51 (between the years 2000 - 2020).
$cd dePolo_etal_v6_output/sharm
This directory includes the spherical harmonic expansions of radial displacements and gravitational potential anomalies from the model output.
File: /dePolo_etal_v6_output/dePolo_etal_v6.dimensional_time
Description: This file includes the time step information for the numerical model. The first column is the time step. The second column is the time elapsed since the beginning of the model run in years (i.e., time step 51 - 120 yrs since the start of the model in 1900, means the year is 2020). The third column is the time increment (delta t) of the step.
Directory: /dePolo_etal_v6_output/incr_disp/
Description: The files within this directory are the incremental displacements from time steps 31 thru 51 (from the year 2000 thru 2020) on the SVE model grid. The first column is longitude (degrees), the second column is latitude (degrees), the third column is incremental vertical displacement (meters), the fourth column is incremental south displacement (meters), and the fifth column is incremental east displacement (meters).
Directory: /dePolo_etal_v6_output/sharm/
Description: Files dePolo_etal_v6.tps_sharm.* and dePolo_etal_v6.vtps_sharm.* are spherical harmonic expansions of cumulative and incremental radial (vertical) displacements, respectively, at the surface for time step ' * '. Files dePolo_etal_v6.pttl_sharm.* and dePolo_etal_v6.pttldot_sharm.* are spherical harmonic expansions for total and incremental gravitational potential anomalies, respectively, at the surface for time step ' * '. To determine the rate of displacement (or gravitational potential change), divide the incremental displacement (or incremental gravitational potential) by the time increment, delta t, for the respective time step. Please see page 24 of the CitcomSVE-3.0 user guide for more information about these output files (https://github.com/shjzhong/CitcomSVE/blob/CitcomSVE-3.0/CitcomSVE3.0_UserGuide.pdf).
Code/software
CitcomSVE-3.0 is the required open-source software to run these models.
Access information
- Users can download CitcomSVE-3.0 and its user guide from Github at https://github.com/shjzhong/CitcomSVE/tree/CitcomSVE-3.0 and https://github.com/shjzhong/CitcomSVE/blob/CitcomSVE-3.0/CitcomSVE3.0_UserGuide.pdf.
- For the grid refinement (higher resolution in West Antarctica), the subroutine ‘full_coord_of_cap’ is included in this repository (/dePolo_etal_inputs/full_coord_of_cap.c). This subroutine in the file ‘Full_sphere_related.c’ (lines 155 - 522) must be replaced, and the code recompiled in order to achieve higher resolution in West Antarctica with CitcomSVE-3.0.