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Data for: Subglacial freshwater driven speedup of East Antarctic outlet glacier retreat

Pelle, Tyler, University of California, San Diego, https://orcid.org/0000-0002-9772-1730
Greenbaum, Jamin, University of California, San Diego
Ehrenfeucht, Shivani, University of Waterloo
Dow, Christine, University of Waterloo
McCormack, Felicity, Monash University
tpelle@ucsd.edu
Published Mar 22, 2024 on Dryad. https://doi.org/10.5061/dryad.1vhhmgr0b

Cite this dataset

Pelle, Tyler et al. (2024). Data for: Subglacial freshwater driven speedup of East Antarctic outlet glacier retreat [Dataset]. Dryad. https://doi.org/10.5061/dryad.1vhhmgr0b

Abstract

Recent studies have revealed the presence of a complex freshwater system underlying the Aurora Subglacial Basin (ASB), a region of East Antarctica that contains ~7 m of global sea level potential in ice mainly grounded below sea level. Yet, the impact that subglacial freshwater has on driving the evolution of the dynamic outlet glaciers that drain this basin has yet to be tested in a coupled ice sheet-subglacial hydrology numerical modeling framework. Here, we project the evolution of the primary outlet glaciers draining the ASB (Moscow University Ice Shelf, Totten, Vanderford, and Adams Glaciers) in response to an evolving subglacial hydrology system and to ocean forcing through 2100, following low and high CMIP6 emission scenarios. By 2100, ice-hydrology feedbacks enhance the ASB’s 2100 sea level contribution by ~30% (7.50 mm to 9.80 mm) in high emission scenarios and accelerate retreat of Totten Glacier’s main ice stream by 25 years. Ice-hydrology feedbacks are particularly influential in the retreat of the Vanderford and Adams Glaciers, driving an additional 10 km of retreat in fully-coupled simulations relative to uncoupled simulations. Hydrology-driven ice shelf melt enhancements are the primary cause of domain-wide mass loss in low emission scenarios, but are secondary to ice sheet frictional feedbacks under high emission scenarios. The results presented here demonstrate that ice-subglacial hydrology interactions can significantly accelerate retreat of dynamic Antarctic glaciers and that future Antarctic sea level assessments that do not take these interactions into account might be severely underestimating Antarctic Ice Sheet mass loss. 

In this data publication, we present the model output and results associated with the following manuscript recently submitted to the Journal of Geophysical Research: Earth Surface: “Subglacial discharge accelerates ocean driven retreat of Aurora Subglacial Basin outlet glaciers over the 21st century”. We include yearly ice sheet model output between 2017-2100 for eight numerical ice-subglacial hydrology model runs. We also include the ice sheet and subglacial hydrology model initial states. In addition, we include all ocean forcing time-series (temperature and salinity for the low emission and high emission climate forcing scenarios for three glacial regions), which are used as input into the melt parameterization. Lastly, we include a MATLAB script that contains the code used to couple the ice-subglacial hydrology models as well as a "readme" file with further information on all data in this publication.

README: Dataset: Subglacial freshwater driven speedup of East Antarctic outlet glacier retreat

https://doi.org/10.5061/dryad.1vhhmgr0b
Journal: Journal of Geophysical Research: Earth Surface

Principle Investigator:

  • Tyler Pelle, Scripps Institution of Oceanography, University of California San Diego, tpelle@ucsd.edu

Co-Authors:

  • Dr. Jamin Greenbaum, Scripps Institution of Oceanography, University of California San Diego
  • Dr. Shivani Ehrenfeucht, Department of Geography and Environmental Management, University of Waterloo
  • Prof. Christine Dow, Department of Geography and Environmental Management, University of Waterloo
  • Dr. Felicity S. McCormack, Securing Antarctica's Environmental Future, School of Earth, Atmosphere, & Environment, Monash University

Created on October 4, 2023

Description of the data and file structure

File description:

  1. runme.m - MATLAB script used to run coupled ISSM-GlaDS SSP5-8.5_{F,M} simulation - includes melt rate parameterization.
  2. ssp585.mat – Yearly ice sheet model output from 2017-2100 for SSP5-8.5 simulation.
  3. ssp585_F.mat – Yearly ice sheet model output from 2017-2100 for SSP5-8.5_{F} simulation.
  4. ssp585_M.mat – Yearly ice sheet model output from 2017-2100 for SSP5-8.5_{M} simulation.
  5. ssp585_FM.mat – Yearly ice sheet model output from 2017-2100 for SSP5-8.5_{F,M} simulation.
  6. ssp126.mat – Yearly ice sheet model output from 2017-2100 for SSP1-2.6 simulation.
  7. ssp126_F.mat – Yearly ice sheet model output from 2017-2100 for SSP1-2.6_{F} simulation.
  8. ssp126_M.mat – Yearly ice sheet model output from 2017-2100 for SSP1-2.6_{M} simulation.
  9. ssp126_FM.mat – Yearly ice sheet model output from 2017-2100 for SSP1-2.6_{F,M} simulation.
  10. ssp585_Totten_T.mat - Bi-weekly ocean temperature (Ta) for Totten Glacier from January 1, 2017 to December 31, 2099 (high emission).
  11. ssp585_Moscow_T.mat - Bi-weekly ocean temperature (Ta) for Moscow University Glacier from January 1, 2017 to December 31, 2099 (high emission).
  12. ssp585_Vander_T.mat - Bi-weekly ocean temperature (Ta) for Vander Glacier from January 1, 2017 to December 31, 2099 (high emission).
  13. ssp585_Totten_S.mat - Bi-weekly ocean salinity (Sa) for Totten Glacier from January 1, 2017 to December 31, 2099 (high emission).
  14. ssp585_Moscow_S.mat - Bi-weekly ocean salinity (Sa) for Moscow University Glacier from January 1, 2017 to December 31, 2099 (high emission).
  15. ssp585_Vander_S.mat - Bi-weekly ocean salinity (Sa) for Vander Glacier from January 1, 2017 to December 31, 2099 (high emission).
  16. ssp126_Totten_T.mat - Bi-weekly ocean temperature (Ta) for Totten Glacier from January 1, 2017 to December 31, 2099 (low emission).
  17. ssp126_Moscow_T.mat - Bi-weekly ocean temperature (Ta) for Moscow University Glacier from January 1, 2017 to December 31, 2099 (low emission).
  18. ssp126_Vander_T.mat - Bi-weekly ocean temperature (Ta) for Vander Glacier from January 1, 2017 to December 31, 2099 (low emission).
  19. ssp126_Totten_S.mat - Bi-weekly ocean salinity (Sa) for Totten Glacier from January 1, 2017 to December 31, 2099 (low emission).
  20. ssp126_Moscow_S.mat - Bi-weekly ocean salinity (Sa) for Moscow University Glacier from January 1, 2017 to December 31, 2099 (low emission).
  21. ssp126_Vander_S.mat - Bi-weekly ocean salinity (Sa) for Vander Glacier from January 1, 2017 to December 31, 2099 (low emission).
  22. TotBasin.exp - Polygon that contains Totten Glacier over which Totten's ocean temperature is applied.
  23. MuisBasin.exp - Polygon that contains Moscow University Glacier over which Totten's ocean temperature is applied.
  24. VandBasin.exp - Polygon that contains Vanderford Glacier over which Totten's ocean temperature is applied.

File specific information:

ASB_IceHydroModel.mat: All data associated with the ice sheet and subglacial hydrology model initial state is held in ASB_IceHydroModel.mat, which contains a MATLAB ‘model’ object (for more information, see https://issm.jpl.nasa.gov/documentation/modelclass/. In MATLAB, the model can be loaded and displayed by running load(‘ASB_IceHydroModel.mat’), which will load in the model variable ‘md’. Of particular interest will be the following data contained in md: md.mesh (mesh information), md.geometry (initial ice sheet geometry, ice shelf geometry, and bed topography), md.hydrology (initial hydrology model fields), md.initialization (model initialization fields) and md.mask (ice mask and grounded ice mask). Note that all fields are defined on the mesh nodes, and one can plot a given field in MATLAB using the ISSM tool ‘plotmodel’ (e.g., plotmodel(md,'data',md.geometry.bed) will plot the model bed topography). For more information on plotting, please see https://issm.jpl.nasa.gov/documentation/plotmatlab/.

Model output files (e.g. ssp585_FM.mat): Yearly ice sheet model results between 2017-2100 for all model simulations described in the paper. Fields appended with '' are included in results with changing subglacial hydrology (ssp126_F, ssp126_M, ssp126_FM, ssp585_F, ssp585_M, ssp585_FM). Fields appended with '*' are included in results where ice shelf melt is enhanced by subglacial discharge (ssp126_M, ssp126_FM, ssp585_M, ssp585_FM). These files contain a MATLAB variable that is the same as the file name, which is a model object of size 1x83 that contains the following yearly variables:

  • * Vel (velocity norm, m/yr)
  • * Thickness (ice sheet thickness, m)
  • * Surface (ice sheet surface elevation, m)
  • * Base (ice sheet base elevation, m)
  • * BasalforcingsFloatingiceMeltingRate (ice shelf basal melting rate field, m/yr)
  • * MaskOceanLevelset (ground ice mask, grounded ice if > 0, grounding line position if = 0, floating ice if < 0)
  • * IceVolume (total ice volume in the model domain, t)
  • * IceVolumeAboveFloatation (total ice volume in the model domain that is above hydrostatic equilibrium, t)
  • * TotalFloatingBmb (Total floating basal mass balance, Gt)
  • * \*ChannelDischarge\_Node (GlaDS-computed channel discharge interpolated onto model node, m3/s)
  • * \*ChannelDiameter\_Node (GlaDS-computed channel diameter interpolated onto model node, m)
  • * \*ChannelArea (GlaDS-computed channel area defined on model edges, m2)
  • * \*ChannelDischarge (GlaDS\_computed channel discharge defined on model edges, m3/s)
  • * \*EffectivePressure (GlaDS-computed ice sheet effective pressure, Pa)
  • * \*HydraulicPotential (GlaDS computed hydraulic potential, -
  • * \*HydrologySheetThickness (GlaDS-computed after sheet thickness, m)
  • * \*GroundedIceMeltingRate (Grounded ice melting rate defined on all grounded nodes, m/yr)
  • * \*\*melt\_nodis (ice shelf basal melting rate computed when discharge is set to zero, m/yr)
  • * \*\*zgl (grounding line height field, m)
  • * \*\*glfw (grounding line fresh water flux field, m2/s)
  • * \*\*chan\_wid (Domain average subglacial discharge channel width, m)
  • * \*\*maxdist (5L' length scale used in melt computation, m)
  • * \*\*maxis (maximum discharge at each subglacial outflow location, m2/s)
  • *\*\_T.mat*: Bi-weekly ocean temperature extracted from an East Antarctic configuration of the MITgcm (Pelle et al., 2021), where '\*' ssp126 (low emission) or ssp585 (high emission). Ocean temperature was averaged adjacent to each target ice front in both depth and in the contours shown in figure 1b.
  • *\*\_S.mat*: Same as above, but for salinity in units on the Practical Salinity Scale (PSU).
  • *.exp: Exp files that contain coordinates that outline a polygon for the drainage basins of each major glacier in this study (Vanderford Glacier contains the drainage basins for Adams, Bond, and Underwood Glaciers as well).

Methods

Ice sheet model results: Direct results taken from the Ice-sheet and Sea-level System Model (ISSM, Larour et al. 2012) with no processing applied, provided yearly as *.mat files.

Ice sheet and subglacial hydrology model initial states: Initial state of the ice sheet model (ice geometry, mesh information, inversion results, etc.) and subglacial hydrology model (steady-state water column thickness, effective pressure, channelized discharge, etc.) containing Aurora Subglacial Basin outlet glaciers with no processing applied, provided as a *.mat file. The contents of the *.mat file is a MATLAB variable of class "model", which is compatible with ISSM. 

Model coupling script: Documented MATLAB script ready to run with the provided data sets.

Ocean temperature and salinity timeseries: Bottom ocean temperature (°C) and salinity (PSU) timeseries  (January 1st, 2017 through December 31, 2099) extracted from an East Antarctic configuration of the ocean component of the MITgcm (Pelle et al., 2021). Temperature and salinity are provided bi-weekly and averged both in depth and along the ice fronts of Moscow University, Totten, and Vanderford Glaciers (see white dashed contour in figure 1b of the main manuscript text). Data are provided as *.mat files.

Polygons that provide locaion to apply ocean temperature and salinity: Polygons provided as a list of x/y coordinates (meters) are provided in three *.exp files that cover the drainage basins of Moscow University, Totten, and Vanderford Glaciers (the polygon for Vanderford also includes the drainage basins of Adams, Bond, and Underwood Glaciers). 

Funding

National Aeronautics and Space Administration, Award: 80NSSC22K0387, Cryosphere Program

National Science Foundation, Award: OPP-2114454, Office of Polar Programs

Australian Research Council, Award: DE210101433, Discovery Early Career Research Award

Australian Research Council, Award: SR200100005, Special Research Initiative

Research Council of Canada, Award: RGPIN-03761-2017, Natural Sciences and Engineering