--------------------------------------------------------------------------------------------------------------------------- GDEMM2024: 30 Arcsec Global Digital Elevation Merged Model 2024, a suite for Earth relief ---------------------------------------------------------------------------------------------------------------------------- Contact: E. Sinem Ince German Research Centre for Geosciences GFZ-Potsdam elmas.sinem.ince@gfz-potsdam.de Created 04-04-2024 ----------------------------------------------------------------------------------------------------------------------------- Please use the following citation for acknowledging the use of the GDEMM2024: Abrykosov, Oleh; Ince, E. Sinem; Foerste, Christoph (2024): GDEMM2024: 30 Arcsec Global Digital Elevation Merged Model 2024, a suite for Earth relief. GFZ Data Services. https://doi.org/10.5880/GFZ.1.2.2024.002 ----------------------------------------------------------------------------------------------------------------------------- License: Creative Commons Attribution 4.0 International (CC BY 4.0); http://creativecommons.org/licenses/by/4.0/ ----------------------------------------------------------------------------------------------------------------------------- 1. SUMMARY ------------ GDEMM2024 consists of elevation grids that represent Earth's relief layers which are topography (surface - SUR), bedrock (BED) and ice (ice thickness - ICE). Earth's relief without water (Topography-Bathymetry-ICE, TBI) which consists of bedrock and ice layers is included for visualisation purposes, whereas GEO can be used to transform heights above the EIGEN-6C4 geoid into WGS84 ellipsoidal heights. GDEMM2024 is provided in 30 arc-sec resolution and for practical reasons also in 1 arc-min resolution. The grids are provided in GeoTIFF format and can be downloaded from: https://doi.org/10.5880/GFZ.1.2.2024.002. 2. INPUT DATA ------------- The GDEMM2024 is merged using the following data sets: - TanDEM-X (Wessel et al. 2018) which represents surface over dry land and ice-covered areas - ETOPO2022, is a combined model and represents global topography and bathymetry - GEBCO_2022, is a combined, SRTM15+ v2.4 base over land, GMTED2010, Seabed2030, dedicated over oceans - GEBCO_2023, an updated version of GEBCO_2022, combined, SRTM15+ v2.5.5 base over land, similar data as in GEBCO_2022, dedicated over oceans - BedMachine v5 Greenland (Morlinghem et al. 2017, Morlinghem et al. 2022) which is a dedicated product that represents ice thickness and bedrock over Greenland - BedMachine v3 Antarctica (Morlinghem et al. 2022) which is a dedicated product developed to represent the ice thickness and bedrock over Antarctica - Hydrosheds (Khazaei et al 2022), dedicated inland lake database which represent the surface areas, surface elevations and depths for about 1.5 Mio lakes and reservoirs worldwide 3. PROCESSING PROCEDURES ------------------------ The merging procedure has been conducted in a strategic sequence based on the accuracy assessments of the data sets. First, a weighted average of ETOPO22, GEBCO_2022, and GEBCO_2023 has been calculated Which is then again weighted averaged with TanDEM-X. For detailed explanation, please refer to the manuscript (draft available upon request) and EGU24 poster presentation (https://meetingorganizer.copernicus.org/EGU24/EGU24-8340.html). Förste, C., Abrykosov, O., and Ince, E. S.: A consolidated 30 Arc-second Global Digital Elevation Model for Geodesy and Geophysics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8340, https://doi.org/10.5194/egusphere-egu24-8340, 2024. 4. GDEMM2024 PRODUCTS and FILE FORMATS ----------------------------------------- We provide the gridded elevation data for topography, bedrock, ice thickness, Earth without water (bedrock and ice), and geoid model to transform height above geoid into ellipsoidal heights. All the grid files are provided in GeoTIFF format. GeoTIFF format is well known and widely used. GMT (Generic Mapping Tools) or GDAL can be used to read the data. For instance grid information can be retrieved using the following: 1) gdalinfo GDEMM2024_SUR.30s.tif 2) gmt grdinfo GDEMM2024_SUR.30s.tif 1) option would lead to the following output: Driver: GTiff/GeoTIFF Files: GDEMM2024_SUR.30s.tif Size is 43200, 21600 Coordinate System is: GEOGCRS["WGS 84 (G1150)", DYNAMIC[ FRAMEEPOCH[2001]], DATUM["World Geodetic System 1984 (G1150)", ELLIPSOID["WGS 84",6378137,298.257223563, LENGTHUNIT["metre",1]]], PRIMEM["Greenwich",0, ANGLEUNIT["degree",0.0174532925199433]], CS[ellipsoidal,2], AXIS["geodetic latitude (Lat)",north, ORDER[1], ANGLEUNIT["degree",0.0174532925199433]], AXIS["geodetic longitude (Lon)",east, ORDER[2], ANGLEUNIT["degree",0.0174532925199433]], USAGE[ SCOPE["Geodesy. Navigation and positioning using GPS satellite system."], AREA["World."], BBOX[-90,-180,90,180]], ID["EPSG",9055]] Data axis to CRS axis mapping: 2,1 Origin = (-179.999999999999659,90.000000000000000) Pixel Size = (0.008333333333333,-0.008333333333333) Metadata: AREA_OR_POINT=Area Image Structure Metadata: INTERLEAVE=BAND Corner Coordinates: Upper Left (-180.0000000, 90.0000000) (180d 0' 0.00"W, 90d 0' 0.00"N) Lower Left (-180.0000000, -90.0000000) (180d 0' 0.00"W, 90d 0' 0.00"S) Upper Right ( 180.0000000, 90.0000000) (180d 0' 0.00"E, 90d 0' 0.00"N) Lower Right ( 180.0000000, -90.0000000) (180d 0' 0.00"E, 90d 0' 0.00"S) Center ( 0.0000000, 0.0000000) ( 0d 0' 0.00"E, 0d 0' 0.00"N) Band 1 Block=43200x1 Type=Int16, ColorInterp=Gray Min=-417.000 Max=8377.000 Minimum=-417.000, Maximum=8377.000, Mean=378.659, StdDev=856.996 NoData Value=-32767 Metadata: STATISTICS_MAXIMUM=8377 STATISTICS_MEAN=378.65916152481 STATISTICS_MINIMUM=-417 STATISTICS_STDDEV=856.99633117435 STATISTICS_VALID_PERCENT=100 5) Relief layers ----------------------------------------------------------------------- GDEMM2024 is available in terms of (1) the physical surface SUR, (2) bedrock BED (Earth`s relief without water and ice masses), (3) ice thicknesses (ICE), (4) topography, bedrock and ice TBI (Earth without water masses), Additionally, we provide (5) Land-type mask (LTM), (6) EIGEN-6C4 geoid (GEO) All grid files are given w.r.t. the EIGEN-6C4 geoid (Foerste et al., 2014) in the WGS84(G1150) datum (EPSG code: 9055). Table 1 - GDEMM2024 layers and their representation -------------------------------------------------------------------------------------------------- Layer Representation Oceans Dry land Lakes Ice-covered areas -------------------------------------------------------------------------------------------------- SUR Surface 0 Topography Surface Surface BED Bedrock Bedrock Topography Bedrock Bedrock ICE Ice over land/shelf 0 0 0 Ice thickness TBI Topography, bedrock, ice Bedrock Topography Bedrock Surface --------------------------------------------------------------------------------------------------- Table 2a - filenames of the relief layers (30 arc-sec resolution) --------------------------------------------------------------------------- Layer Filename Filesize Format (binary) --------------------------------------------------------------------------- SUR GDEMM2024_SUR.30s.tif 1.8G Int16, "ieee-le" BED GDEMM2024_BED.30s.tif 1.8G Int16, "ieee-le" ICE GDEMM2024_ICE.30s.tif 1.8G Int16, "ieee-le" TBI GDEMM2024_TBI.30s.tif 1.8G Int16, "ieee-le" -------------------------------------------------------------------------- LTM GDEMM2024_LTM.30s.tif 1.8G Int16, "ieee-le" GEO GDEMM2024_GEO.30s.tif 1.8G Int16, "ieee-le" -------------------------------------------------------------------------- Table 2b - filenames of the relief layers (1 arc-min resolution) --------------------------------------------------------------------------- Layer Filename Filesize Format (binary) --------------------------------------------------------------------------- SUR GDEMM2024_SUR.1m.tif 446M Int16, "ieee-le" BED GDEMM2024_BED.1m.tif 446M Int16, "ieee-le" ICE GDEMM2024_ICE.1m.tif 446M Int16, "ieee-le" TBI GDEMM2024_TBI.1m.tif 446M Int16, "ieee-le" -------------------------------------------------------------------------- LTM GDEMM2024_LTM.1m.tif 446M Int16, "ieee-le" GEO GDEMM2024_GEO.1m.tif 446M Int16, "ieee-le" -------------------------------------------------------------------------- Mask grid values for land types -------------------------------------------------------------------------- 0 - ocean, 1 - dry land, 2 - inland lake, 3 - ice covered land, 4 - ice covered shelf, 5 - ice covered lake (Vostok). REFERENCES ---------- ETOPO22: NOAA National Centers for Environmental Information. 2022: ETOPO 2022 15 Arc-Second Global Relief Model. NOAA National Centers for Environmental Information. https://doi.org/10.25921/fd45-gt74 Förste, C., Bruinsma, Sean. L., Abrikosov, O., Lemoine, J.-M., Marty, J. C., Flechtner, F., Balmino, G., Barthelmes, F., & Biancale, R. (2014). EIGEN-6C4 The latest combined global gravity field model including GOCE data up to degree and order 2190 of GFZ Potsdam and GRGS Toulouse [dataset]. GFZ Data Services. https://doi.org/10.5880/ICGEM.2015.1 Fretwell, P., Pritchard, H. D., Vaughan, D. G., Bamber, J. L., Barrand, N. E., Bell, R., ... & Zirizzotti, A. (2013). Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. The cryosphere, 7(1), 375-393, https://doi.org/10.5194/tc-7-375-2013 GEBCO Compilation Group (2022) GEBCO_2022 Grid (https://doi.org/10.5285/e0f0bb80-ab44-2739-e053-6c86abc0289c). GEBCO Compilation Group (2023) GEBCO 2023 Grid (https://doi.org/10.5285/f98b053b-0cbc-6c23-e053-6c86abc0af7b). Hirt, C., & Rexer, M. (2015). Earth2014: 1 arc-min shape, topography, bedrock and ice-sheet models–available as gridded data and degree-10,800 spherical harmonics. International Journal of Applied Earth Observation and Geoinformation, 39, 103-112, https://doi.org/10.1016/j.jag.2015.03.001 Khazaei, B., Read, L. K., Casali, M., Sampson, K. M., & Yates, D. N. (2022). GLOBathy, the global lakes bathymetry dataset. Scientific Data, 9(1), 36, https://doi.org/10.1038/s41597-022-01132-9 Morlighem, M., Williams, C. N., Rignot, E., An, L., Arndt, J. E., Bamber, J. L., ... & Zinglersen, K. B. (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, https://doi.org/10.1002/2017GL074954 Morlighem, M., Rignot, E., Binder, T., Blankenship, D., Drews, R., Eagles, G., ... & Young, D. A. (2020). Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet. Nature geoscience, 13(2), 132-137, https://doi.org/10.1038/s41561-019-0510-8 Morlighem, M. (2022). MEaSUREs BedMachine Antarctica, Version 3. [bed, geoid, mask, surface, thickness, x, y]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/FPSU0V1MWUB6 Morlighem, M., Williams, C., Rignot, E., An, L., Arndt, J. E., Bamber, J., & Zinglersen, K. (2022). IceBridge BedMachine Greenland, Version 5. [bed, geoid, mask, surface, thickness, x, y]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/GMEVBWFLWA7X Wessel, B. (2018). TanDEM-X Ground Segment - DEM Products Specification Document, EOC, ELR, Oberpfaffenhofen, Germany, Public Document TD-GS-PS-0021, Issue 3.2, 2018. Available: https://tandemx-science.dlr.de [accessed at 08 April 2024) Wessel, B., Huber, M., Wohlfart, C., Marschalk, U., Kosmann, D., & Roth, A. (2018). Accuracy assessment of the global TanDEM-X Digital Elevation Model with GPS data. ISPRS Journal of Photogrammetry and Remote Sensing, 139, 171-182, https://doi.org/10.1016/j.isprsjprs.2018.02.017 Wessel, P., Luis, J. F., Uieda, L. A., Scharroo, R., Wobbe, F., Smith, W. H., & Tian, D. (2019). The generic mapping tools version 6. Geochemistry, Geophysics, Geosystems, 20(11), 5556-5564, https://doi.org/10.1029/2019GC008515 DISCLAIMER ---------- Neither GFZ nor any of its staff provide any warranty concerning the accuracy and the use of the data set provided.