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Data from: Widespread grounding line retreat of Totten Glacier, East Antarctica, over the 21st century

Citation

Pelle, Tyler; Morlighem, Mathieu; Seroussi, Helene; Nakayama, Yoshihiro (2021), Data from: Widespread grounding line retreat of Totten Glacier, East Antarctica, over the 21st century, Dryad, Dataset, https://doi.org/10.7280/D1KD7C

Abstract

Totten Glacier, the primary ice discharger of East Antarctica, contains 3.85 m sea level rise equivalent ice mass (SLRe) and has displayed ocean-driven dynamic change since at least the early 2000s. We project Totten’s evolution through 2100 in a fully coupled ice-ocean model, forced at the ocean boundaries with anomalies in CMIP6 projected temperature, salinity, and velocity. Consistent with previous studies, the Antarctic Slope Current continues to modulate warm water inflow towards Totten in future simulations. Warm water (-0.5-1oC) accesses Totten’s sub-ice shelf cavity through depressions along the eastern ice front, driving sustained retreat of Totten’s eastern grounding zone that cannot be captured in uncoupled models. In high emission scenarios, warm water overcomes topographic barriers and dislodges Totten’s southern grounding zone around 2070, increasing the rate of grounded ice loss 3.5-fold (10 to 35 Gt/yr) and resulting in a total 4.20 mm SLRe loss by 2100.

In this data publication, we present the model output and results associated with the Geophysical Research Letter's manuscript 2021GL093213: “Widespread grounding line retreat of Totten Glacier, East Antarctica, over the 21st century”. We include all coupled and uncoupled ice sheet model results and the initial-state ice sheet model. In addition, we include the temperature, salinity and velocity mean rate-of-change fields that were applied to the northern, eastern, and western ocean boundaries following CMIP6 low and high emission scenarios. We also include example ocean model output from the initial ocean model state and at 2070 for all coupled experiments, an ocean model data file that details the setup and grid of the ocean model, and the ocean model bathymetry and initial ice shelf draft files. Lastly, we include the time series of the mean strength of the Antarctic Slope Current for all couped experiments, as well as the script used to facilitate coupling between the ice sheet and ocean model. Please note that we do not include all ocean model output, as the number and size of the associated files is too large; however, the data available here is sufficient to reproduce all manuscript figures and recreate the model-coupling.

Methods

Ice sheet model results: Direct results taken from the Ice-sheet and Sea-level System Model (Larour et al. 2012) with no processing applied, given bi-monthly.

Ocean model results: Direct results taken from the MIT General Circulation Model (MITgcm, Marshall and Clarke, 1997) with no processing applied.

Strength of the Antarctic Slope Current: The east-west component of the ocean velocity (direct output of the MITgcm) was averaged at 118oC along the continental slope at depths between 280-820 m from January 1, 2017 to December 15, 2099 (bi-weekly).

Ice shelf draft: Direct output from BedMachine Antarctica (Morlighem et al., 2020) over ice covered regions of the ocean model domain, no processing has been applied.

Ocean bathymetry: Bathymetry below floating ice is taken from BedMachine Antarctica (Morlighem et al., 2020) and from ETOPO1 over open ocean (National Geophysical Data Center), with recent updates of more accurate bathymetry for the region on the continental shelf off Totten ice shelf from Rintoul et al. (2016). Data was linearly interpolated between the different data sets to allow for a smooth transition.

Ocean boundary forcing files: Monthly CMIP6 projected ocean temperature (T), salinity (S), east-west velocity (U), and north-south velocity (V) was extracted along the ocean model boundaries (northern, eastern, and western) between January 2017 and December 2100 following low (SSP126) and high (SSP585) emission scenarios from four global climate models: CNRM-CM6-1, CNRM-ESM2-1, UKESM1-0-LL, and MIROC-ES2L. At every grid cell along a given boundary, we compute the rate of change of a given field between 2017 and 2100, providing us with rates of change in ocean T, S, U, and V for each global climate model. At each boundary, we then model-average of these rate of change fields with respect to a specific variable. In the end, we are provided with anomalies in T, S, U, and V at the eastern, western, and northern ocean model boundaries.