This data set contains a bed topography and bathymetry map of Greenland based on mass conservation, multi-beam data, and other techniques. It also includes surface elevation and ice thickness data, as well as an ice/ocean/land mask.

This data set contains bed topography beneath the Greenland Ice Sheet based on mass conservation derived from airborne radar tracks and satellite radar. The data set also includes surface and ice thickness measurements.

This data set contains a bed topography/bathymetry map of Greenland based on mass conservation, multi-beam data, and other techniques. It also includes surface elevation and ice thickness data, as well as an ice/ocean/land mask.

This data set contains bed topography beneath the Greenland Ice Sheet based on mass conservation derived from airborne radar tracks and satellite radar. The data set also includes surface and ice thickness measurements.

Mass flow rate ice discharge (MFID) for Greenland ice sheet sectors. This data set is part of the ESA Greenland Ice sheet CCI project.

It provides the following CSV files: - Mass flow rate ice discharge. Units are Gt yr^{-1}. - Mass flow rate ice discharge uncertainty. Units are Gt yr^{-1}. - Coverage for each sector at each timestamp. Unitless [0 to 1].

Ice discharge is calculated from the CCI Ice Velocity (IV) product, the CCI Surface Elevation Change (SEC) product (where it overlaps with the ice discharge gates), and ice thickness from BedMachine. Ice discharge gates are placed 10 km upstream from all marine terminating glacier termini that have baseline velocities of more than 150 m/yr. Results are summed by Zwally et al. (2012) sectors.

The methods, including description of "coverage", are described in Mankoff et al. 2020.

This dataset contains frontal ablation estimates for 49 tidewater glaciers in Greenland which have been calculated using the following open source remote sensing 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; Porter et al., 2018, Korsgaard et al., 2016)
5. Surface change rate (Khan, 2017)
6. Bedrock Topography (BedMachine v4; Morlighem et al., 2017, 2021).
7. Solid Ice Discharge (Mankoff, 2019)

The dataset contains the following variables for each tidewater glacier:

• tbounds - boundaries of time intervals on which output data defined
• t - midpoint of time intervals on which output data defined
• D - discharge during time intervals [GT/yr]
• TMC - terminus mass change during time intervals [GT/yr]
• FA - frontal ablation during time intervals [GT/yr]
• D0 - discharge masking out interpolated values [GT/yr]
• TMC0 - terminus mass change masking out interpolated values [GT/yr]
• FA0 - frontal ablation masking out interpolated values [GT/yr]
• Error - Maximum error during time interval [GT/yr]

Note: The variable "tbounds" contains the boundary dates for the investigated time period while the frontal ablation estimates correspond to the midpoints of the time intervals. Therefore the last time boundary does not contain any estimates and is set to NaN.

The processing chain to derive these frontal ablation estimates is described in Fahrner et al., (2023) and can been found at https://zenodo.org/records/8414730. A tutorial on how to use the processing chain is available on GitHub (https://github.com/DominikFahrner/TG_FACT)

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When using this data set please cite:

Fahrner, D., Slater, D., KC, A., Cenedese, C., Sutherland, D.A., Enderlin, E., de Jong, F., Kjeldsen, K.K., Wood, M., Nienow, P. Nowicki, S., Wagner, T. (2023): A Frontal Ablation Dataset for 49 Tidewater Glaciers in Greenland

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References

Goliber, S. and Black, T., (2021) TermPicks: A century of Greenland glacier terminus data for use inmachine learning applications. [online] Available at: https://zenodo.org/record/5117931 [Accessed 27 May 2022].

Khan, S.A., (2017) Greenland Ice Sheet Surface Elevation Change. Available at: http://promice.org/PromiceDataPortal/api/download/90fb4cbf-e88e-4e26-af95-a47d19a9cf10.

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. Scientific Data, [online] 31, p.160032. Available at: https://doi.org/10.1038/sdata.2016.32.

Mankoff, K.D., (2019) Ice dicharge for the Greenland ice sheet. Available at: https://doi.org/10.22008/PROMICE/DATA/ICE_DISCHARGE.

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.

Morlighem, M., Williams, C.N., Rignot, E., An, L., Arndt, J.E., Bamber, J.L., 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.A.-N.S.F., (2018) ArcticDEM. V1 ed. Available at: https://doi.org/10.7910/DVN/OHHUKH.

This dataset contains supporting data accompanying Culberg, R., Michaelides, R. J., and Miller, J. Z.: Sentinel-1 Detection of Ice Slabs on the Greenland Ice Sheet, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-2652, 2023. The final accepted manuscript will be linked via the same preprint server at the time of publication. The dataset contains the following files:

Sentinel-1 HV and HV/HH backscatter mosaics of the Greenland Ice Sheet formed using data from 1 Oct 2016 - 30 April 2017.

Estimated average annual summer melt extent between 1 Nov 2014 and 31 Aug 2020, detected using seasonal variations in Sentinel-1 HH backscatter.

The firn aquifer extent over Greenland derived from Sentinel-1 in Brangers et al. (2020), reprojected to EPSG:3413.

The ice mask used in the study, derived from the BedMachine Greenland ice mask.

The training and validation datasets derived from the Jullien et al. (2023) ice slabs detections from ice penetrating radar data that were used to optimize ice slab detection thresholds for the Sentinel-1 backscatter mosaics.

We present a 1986 through March 2020 estimate of Greenland Ice Sheet ice discharge. Our data include all discharging ice that flows faster than 100 m yr−1 and are generated through an automatic and adaptable method, as opposed to conventional handpicked gates. We position gates near the present-year termini and estimate problematic bed topography (ice thickness) values where necessary. In addition to using annual time-varying ice thickness, our time series uses velocity maps that begin with sparse spatial and temporal coverage and end with near-complete spatial coverage and 12 d updates to velocity. The 2010 through 2019 average ice discharge through the flux gates is  ~487 +/- 49 Gt yr−1. The 10 % uncertainty stems primarily from uncertain ice bed location (ice thickness). We attribute the ∼50 Gt yr−1 differences among our results and previous studies to our use of updated bed topography from BedMachine v3. Discharge is approximately steady from 1986 to 2000, increases sharply from 2000 to 2005, and then is approximately steady again. However, regional and glacier variability is more pronounced, with recent decreases at most major glaciers and in all but one region offset by increases in the northwest region through 2017 and in the southeast from 2017 through March 2020. As part of the journal's living archive option and our goal to make an operational product, all input data, code, and results from this study will be updated as needed (when new input data are available, as new features are added, or to fix bugs) and made available at https://doi.org/10.22008/promice/data/ice_discharge (Mankoff, 2020a) and at https://github.com/mankoff/ice_discharge (last access: 6 June 2020, Mankoff, 2020e). Mankoff, Ken; Hillerup, Signe, 2020, "Greenland Ice Sheet solid ice discharge from 1986 through last month: Gates", https://doi.org/10.22008/promice/data/ice_discharge/gates/v02, GEUS Dataverse, V6

Abstract:

These data products accompany the paper "Stochastic Modeling of Subglacial Topography Exposes Uncertainty in Water Routing at Jakobshavn Glacier" (MacKie et al., in review). In this study, geostatistical techniques were used to generate an ensemble of topographic realizations that retain the spatial statistics of radar bed elevation measurements. The simulation was conditioned to local radar data and mass conservation bed estimates. This repository contains the radar and mass conservation conditioning data, the ensemble of topographic realizations, and coordinate data.

Content and processing steps:

The study area is 75.15 x 48.90 km^2. The grid cell resolution is 150 meters. Each digital elevation model (DEM) has 501 x 326 grid cells. The mass conservation DEM was obtained from BedMachine Greenland (Morlighem and others, 2017). The radar data were acquired from the Center for Remote Sensing of Ice Sheets (CReSIS) 2009 flights (Gogineni, 2012; Gogineni and others, 2014). A probabilistic modeling technique called sequential Gaussian co-simulation (Verly, 1993; Almeida and Journel, 1994; Journel, 1999; Remy, 2005) was used to generate the topographic realizations. The datasets are as follows:

1) Jakobshavn_mass_conservation.txt - Mass conservation conditioning data

2) Jakobshavn_radar_data.txt - Radar conditioning data

3) Jakobshavn_simulation.txt - 250 topographic realizations. The shape of this file is 250 x 163326, where each column corresponds to one topographic realization. Each column should be reshaped to 501 x 326 to view the DEM.

4) Jakobshavn_x_data.txt - Polar stereographic X coordinates in meters

5) Jakobshavn_y_data.txt - Polar stereographic Y coordinates in meters

References:

Almeida, A. S., & Journel, A. G. (1994). Joint simulation of multiple variables with a Markov-type coregionalization model. Mathematical Geology, 26(5), 565-588.

Gogineni, P. (2012). CReSIS radar depth sounder data. Center for Remote Sensing of Ice Sheets, Lawrence, KS https://data. cresis.-ku. edu.

Gogineni, S., Yan, J. B., Paden, J., Leuschen, C., Li, J., Rodriguez-Morales, F., ... & Gauch, J. (2014). Bed topography of Jakobshavn Isbræ, Greenland, and Byrd Glacier, Antarctica. Journal of Glaciology, 60(223), 813-833.

Journel, A. G. (1999). Markov models for cross-covariances. Mathematical Geology, 31(8), 955-964.

Morlighem, M., Williams, C. N., Rignot, E., An, L., Arndt, J. E., Bamber, J. L., ... & Fenty, I. (2017). BedMachine v3: Complete bed topography and ocean bathymetry mapping of Greenland from multibeam echo sounding combined with mass conservation. Geophysical research letters, 44(21), 11-051.

Remy, N. (2005). S-GeMS: the stanford geostatistical modeling software: a tool for new algorithms development. In Geostatistics banff 2004 (pp. 865-871). Springer, Dordrecht.

Verly, G. W. (1993). Sequential Gaussian cosimulation: a simulation method integrating several types of information. In Geostatistics Troia’92 (pp. 543-554). Springer, Dordrecht.

We employ NASA's Operation IceBridge (OIB) high†resolution airborne gravity from 2016, NASA's Ocean Melting Greenland (OMG) bathymetry from 2015, ice thickness from Operation IceBridge (OIB) from 2010†2015, and BedMachine v3 to analyze 20 major southeast Greenland glaciers. The results reveal glacial fjords several hundreds of meters deeper than previously thought; the full extent of the marine†based portions of the glaciers; deep troughs enabling warm, salty Atlantic Water (AW) to reach the glacier fronts and melt them from below; and few shallow sills that limit the access of AW. The new oceanographic and topographic data help to fully resolve the complex pattern of historical ice front positions from the 1930s to 2017: glaciers exposed to AW and resting on retrograde beds have retreated rapidly, while glaciers perched on shallow sills or standing in colder waters or with major sills in the fjords have remained stable.

Please cite the following paper when using this dataset:

Mil...

Geology is based on field work by Peter R. Dawes in 1971, 1975 and 1978, the latter year with Allen P. Nutman. Compiled with photointerpretation 1988–89, with local revision based on field work in 2001. Apart from northernmost Kangerlussuaq (Inglefield Bredning), the coast was surveyed by boat with sporadic foot traverses, aided by helicopter in 1978 and 2001. Geology of Qaqujaarsuaq (Smithson Bjerge) is based on simplification of the 1:50 000 map by Allen P. Nutman (1984). GIS compilation: Katja T. Walentin, Samuel P. Jackson, Eva Willerslev and Mette S. Jørgensen. Cross sections: Martin Sønderholm; Smithson Bjerge section is based on Nutman (1984). Editorial handling: Thomas F. Kokfelt and Martin Sønderholm. Reviewed by John Grocott (Durham University, United Kingdom) and Marc R. St-Onge (Geological Survey of Canada). Detailed information on the map units is available in the GEUS Greenland Intrusive and Stratigraphic Database using the GU-codes shown in brackets in the legend (https://doi.org/10.22008/FK2/F9MBNJ). Information on mineral occurrences is available in the Greenland Mineral Resources Portal (https://www.greenmin.gl). Topographic base: Geodetic Institute maps at 1:200 000 from 1954 with major revision of the ice margin and glaciers based on 1:150 000 aerial photographs from 1985–1987 and Sentinel 2 satellite scenes from 2019. All heights are in metres. Additional lake heights are from the Danish Agency for Data Supply and Infrastructure (now the Danish Agency for Climate Data): Højdemodel Grønland (https://dataforsyningen.dk/data/4780, accessed September 2023). Ground exposed by ice retreat since initial compilation in 1988–1989 is identified in the legend. 1949 ice margins are from Geodetic Institute maps. Ice margins recorded during expeditions by Robert E. Peary in 1892 and Lauge Koch in 1922 are approximate. Ice altimetry and thickness are based on data from Morlighem et al. (2017), bathymetry is from Morlighem et al. (2022). Authorised place names are from Oqaasileriffik (The Language Secretariat of Greenland), with supplementary names from Laursen (1972). Projection: WGS 84 UTM Zone 20N. Copyright © Geological Survey of Denmark and Greenland. References: Dawes, P.R. 1997: The Proterozoic Thule Supergroup, Greenland and Canada: history, lithostratigraphy and development. Geology of Greenland Survey Bulletin 174, 150 pp. https://doi.org/10.34194/ggub.v174.5025 Dawes, P.R. 2006: Explanatory notes to the Geological map of Greenland, 1:500 000, Thule, Sheet 5. Geological Survey of Denmark and Greenland Map Series 2, 97 pp. + map sheet. https://doi.org/10.34194/geusm.v2.4614 Laursen, D. 1972: The place names of North Greenland. Meddelelser om Grønland 180(2), 443 pp. + 18 plates. Morlighem, M. et al. 2017: BedMachine v3 [Surface; Thickness]: Complete bed topography and ocean bathymetry mapping of Greenland from multibeam echo sounding combined with mass conservation. Geophysical Research Letters 44, 11051–11061. https://doi.org10.1002/2017GL074954 Morlighem, M. et al. 2022: IceBridge BedMachine Greenland, Version 5 [Bed]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/GMEVBWFLWA7X (accessed January 2024). Nutman, A.P. 1984: Precambrian gneisses and intrusive anorthosite of Smithson Bjerge, Thule district, North-West Greenland. Rapport Grønlands Geologiske Undersøgelse 119, 31 pp. + plate. https://doi:10.34194/rapggu.v119.7849 Thomassen, B. & Krebs, J.D. 2004: Mineral exploration of selected targets in the Qaanaaq region, North-West Greenland: follow-up on Qaanaaq 2001. Danmarks og Grønlands Geologiske Undersøgelse Rapport 2004/42, 64 pp. https://doi.org/10.22008/gpub/25622 Thomassen, B., Krebs, J.D. & Dawes, P.R. 2002: Qaanaaq 2001: mineral exploration in the Olrik Fjord – Kap Alexander region, North-West Greenland. Danmarks og Grønlands Geologiske Undersøgelse Rapport 2002/86, 72 pp. + map. https://doi.org/10.22008/gpub/18491

Geology is based on field work by Peter R. Dawes in 1971, 1975 and 1978. Compiled with photointerpretation 1988–89, with local revision based on field work in 2001. The coast was surveyed by boat with sporadic foot traverses, aided by helicopter in 1978 and 2001. GIS compilation: Katja T. Walentin, Samuel P. Jackson, Eva Willerslev and Mette S. Jørgensen. Cross section: Martin Sønderholm. Editorial handling: Thomas F. Kokfelt and Martin Sønderholm. Reviewed by John Grocott (Durham University, United Kingdom) and Marc R. St-Onge (Geological Survey of Canada). Detailed information on the map units is available in the GEUS Greenland Intrusive and Stratigraphic Database using the GU-codes shown in brackets in the legend (https://doi.org/10.22008/FK2/F9MBNJ). Information on mineral occurrences is available in the Greenland Mineral Resources Portal (https://www.greenmin.gl). Topographic base: Geodetic Institute maps at 1:200 000 from 1954 with major revision of the ice margin and glaciers based on 1:150 000 aerial photographs from 1985–1987 and Sentinel 2 satellite scenes from 2019. All heights are in metres. Additional lake heights are from the Danish Agency for Data Supply and Infrastructure (now the Danish Agency for Climate Data): Højdemodel Grønland (https://dataforsyningen.dk/data/4780, accessed September 2023). Ground exposed by ice retreat since initial compilation in 1988–1989 is identified in the legend. 1949 ice margins are from Geodetic Institute maps. Ice margins recorded during expeditions by Robert E. Peary in 1892 and Lauge Koch in 1922 are approximate. Ice altimetry and thickness are based on data from Morlighem et al. (2017), bathymetry is from Morlighem et al. (2022). Landslides are modified from GEUS internal data, for methodology see Svennevig (2019). Authorised place names are from Oqaasileriffik (The Language Secretariat of Greenland), with supplementary names from Laursen (1972). Projection: WGS 84 UTM Zone 20N. Copyright © Geological Survey of Denmark and Greenland. References: Dawes, P.R. 1997: The Proterozoic Thule Supergroup, Greenland and Canada: history, lithostratigraphy and development. Geology of Greenland Survey Bulletin 174, 150 pp. https://doi.org/10.34194/ggub.v174.5025 Dawes, P.R. 2006: Explanatory notes to the Geological map of Greenland, 1:500 000, Thule, Sheet 5. Geological Survey of Denmark and Greenland Map Series 2, 97 pp. + map sheet. https://doi.org/10.34194/geusm.v2.4614 Laursen, D. 1972: The place names of North Greenland. Meddelelser om Grønland 180(2), 443 pp. + 18 plates. Morlighem, M. et al. 2017: BedMachine v3 [Surface; Thickness]: Complete bed topography and ocean bathymetry mapping of Greenlandfrom multibeam echo sounding combined with mass conservation. Geophysical Research Letters 44, 11051–11061. https://doi.org/10.1002/2017GL074954 Morlighem, M. et al. 2022: IceBridge BedMachine Greenland, Version 5 [Bed]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/GMEVBWFLWA7X (accessed January 2024). Svennevig, K. 2019: Preliminary landslide mapping in Greenland. Geological Survey of Denmark and Greenland Bulletin 43,e2019430207. https://doi.org/10.34194/GEUSB-201943-02-07 Thomassen, B., Krebs, J.D. & Dawes, P.R. 2002: Qaanaaq 2001: mineral exploration in the Olrik Fjord – Kap Alexander region, North-West Greenland. Danmarks og Grønlands Geologiske Undersøgelse Rapport 2002/86, 72 pp. + map. https://doi.org/10.22008/gpub/18491

A coastline of Kalaallit Nunaat/ Greenland covering all land and islands, produced in 2017 for the BAS map ''Greenland and the European Arctic''. The dataset was produced by extracting the land mask from the Greenland BedMachine dataset and manually editing anomalous data. Some missing islands were added and glacier fronts were updated using 2017 satellite imagery. The dataset can be used for cartography, analysis and as a mask, amongst other uses. At very large scales, the data will appear angular due to the nature of being extracted from a raster with 150 m cell size, but the dataset should be suitable for use at most scales and can be edited by the user to exclude very small islands if required. The projection of the dataset is WGS 84 NSIDC Sea Ice Polar Stereographic North, EPSG 3413. The dataset does not promise to cover every island and coastlines were digitised using the data creator''s interpretation of the landforms from the images.

The Nippon Foundation-GEBCO Seabed 2030 project has produced a global terrain model for ocean and land. The GEBCO_2023 grid was published in April 2023 and is the fifth GEBCO grid developed through The Nippon Foundation-GEBCO Seabed 2030 Project. This is a collaborative project between the Nippon Foundation of Japan and GEBCO. The Seabed 2030 Project aims to bring together all available bathymetric data to produce the definitive map of the world ocean floor and make it available to all.

The GEBCO_2023 Grid is a continuous, global terrain model for ocean and land with a spatial resolution of 15 arc seconds. Between latitudes of 50° South and 60° North it uses version 2.5.5 of the SRTM15+ dataset as a \"base\". This data set is a fusion of land topography with measured and estimated seafloor topography. This version of SRTM15+ is similar to version 2.1 [Tozer et al., 2019] but includes additional data sets. It uses predicted depths based on the V32 gravity model [Sandwell et al., 2019]. The SRTM15+ base grid has been augmented with the gridded bathymetric data sets developed by the four Seabed 2030 Regional Centers to produce the GEBCO_2023 Grid. Note: SRTM15+ V2.5.5 is also available through OpenTopography here.

The information for ice-surface elevation and under-ice topography/bathymetry is taken from IceBridge BedMachine Greenland, Version 4.6 (Morlighem, M. et al. 2017) and data based on MEaSUREs BedMachine Antarctica, Version 2 (Morlighem, M. et al 2020).

NOTE: This dataset includes under-ice sheet topography. For a version of the dataset with ice surface topography see \"GEBCO IceTopo\" below under \"Other Available Data Products\".

Topographic correction for geothermal heat flux across both Greenland and Antarctica. This dimensionless correction field is derived from a statistical model applied to BedMachine bed topography. Applying this small-scale topographic correction to independent large-scale geothermal heat flux fields renders them more self-consistent with local bed topography.