Tidewater Glacier Frontal Ablation Calculation Tool (TG_FACT)

The processing chain will automatically calculate monthly, three-monthly or annual frontal

ablation estimates for Greenlandic tidewater glaciers.

Input data

1. TermPicks Terminus delineations (Goliber and Black, 2021)
2. Satellite image (for manual delineation of fjord walls).
3. Glacier velocity (code will automatically download ITS_LIVE velocities ~15 GB)
4. Two Digital Elevation Models (preferably ArcticDEM and AeroDEM; (Korsgaard et al., 2016; Porter et al., 2022)
5. Surface change rate ((Khan, 2023)
6. Bedrock Topography from BedMachine v4 Morlighem et al., 2017, 2021)
7.  Solid Ice Discharge (Mankoff et al., 2020)

Output

The resulting data of frontal ablation estimates for each glacier is provided as Matlab and ESRI Shapefile. The full dataset as described in Fahrner et al., (in prep.) is also provided as NetCDF and Geopackage.

• Glacier name – Name of each glacier investigated in this study [unitless]
• F – Three-month-average frontal ablation estimates during time intervals [Gt/d]
• F_Uncertainty – three-month-average frontal ablation uncertainty for time intervals [Gt/d]
• F_Max_Uncertainty – Maximum uncertainty over total time period [Gt/d]
• Date – Midpoint of time intervals on which output data is defined [yyyy-mm-dd]
• D – Three-month-average discharge during time intervals [Gt/d]
• D_Uncertainty – Three-month-average discharge uncertainty for time interval [Gt/d]
• TMC – Terminus mass change (dM/dt) during time intervals [Gt/d]
• TMC _Uncertainty – Three-month-average terminus mass change uncertainty during time intervals [Gt/d]
• Rho – Ice density (constant) [kg/km3]
• L – Interpolated terminus change over time (L) [km]
• Delta_L_W – Delineation and terminus width uncertainty (constant) [km]
• H – Mean ice thickness along the centerline (H) [km]
• Delta H – Ice thickness uncertainty with constant ArcticDEM/AeroDEM uncertainties of 0.1 m and 6 m, respectively [km]
• W – Terminus width (W) [km]
• Bedrock_U – Mean uncertainty in bedrock topography along the centerline [km]
• TI – Time interval over which data are averaged (t2-t1; 90 days for the results presented here) 

A tutorial on how to run the processing chain is available in the "ReadMe" PDF. 

When using this processing chain please use the citation provided in the repository.

The complete dataset associated with the publication can be found at https://zenodo.org/records/13132278. 

References

Goliber, S. and Black, T., (2021) TermPicks: A century of Greenland glacier terminus data for use inmachine learning applications (Version 1). Available at: https://zenodo.org/records/5117931.

Khan, S.A., (2023) Greenland Ice Sheet Surface Elevation Change. Available at: https://doi.org/10.22008/FK2/GQJJEA.

Korsgaard, N.J., Nuth, C., Khan, S.A., Kjeldsen, K.K., Bjørk, A.A., Schomacker, A. and Kjær, K.H., (2016) Digital Elevation Model and orthophotographs of Greenland based on aerial photographs from 1978-1987 (G150 AERODEM) (NCEI Accession 0145405). Available at: https://doi.org/10.7289/v56q1v72.

Mankoff, K.D., Solgaard, A., Colgan, W., Ahlstrøm, A.P., Khan, S.A. and Fausto, R.S., (2020) Greenland Ice Sheet solid ice discharge from 1986 through March 2020. Earth Syst. Sci. Data, [online] 122, pp.1367–1383. Available at: https://essd.copernicus.org/articles/12/1367/2020/.

Morlighem, M., Williams, C., Rignot, E., An, L., Arndt, J.E., Bamber, J., Catania, G., Chauché, N., Dowdeswell, J.A., Dorschel, B., Fenty, I., Hogan, K., Howat, I., Hubbard, A., Jakobsson, M., Jordan, T.M., Kjeldsen, K.K., Millan, R., Mayer, L., Mouginot, J., Noël, B., O’Cofaigh, C., Palmer, S.J., Rysgaard, S., Seroussi, H., Siegert, M.J., Slabon, P., Straneo, F., Broeke, M.R. van den, Weinrebe, W., Wood, M. and Zinglersen, K., (2021) IceBridge BedMachine Greenland, Version 4. Available at: https://doi.org/10.5067/VLJ5YXKCNGXO.

Morlighem, M., Williams, C.N., Rignot, E., An, L., Arndt, J.E., Bamber, J., Catania, G., Chauché, N., Dowdeswell, J.A., Dorschel, B. and others, (2017) BedMachine v3: Complete bed topography and ocean bathymetry mapping of Greenland from multibeam echo sounding combined with mass conservation. Geophysical research letters, 4421.

Porter, C., Morin, P., Howat, I., Noh, M.-J., Bates, B., Peterman, K., Keesey, S., Schlenk, M., Gardiner, J., Tomko, K., Willis, M., Kelleher, C., Cloutier, M., Husby, E., Foga, S., Nakamura, H., Platson, M., Wethington Jr., M., Williamson, C., Bauer, G., Enos, J., Arnold, G., Kramer, W., Becker, P., Doshi, A., D’Souza, C., Cummens, P., Laurier, F. and Bojesen, M.A.-N.S.F., (2022) ArcticDEM, Version 3. V1 ed. Available at: https://doi.org/10.7910/DVN/OHHUKH.