GEBCO Earth Reliefs ------------------- .. figure:: /_static/igpp.png :align: right :scale: 20 % .. figure:: /_static/GMT_earth_gebco.jpg :height: 888 px :width: 1774 px :align: center :scale: 40 % Usage ~~~~~ You access the GEBCO global relief grid by specifying the special name @earth_gebco[_\ *rru*\ [_\ *reg*\ ]] This grid only contains observed relief and inferred relief via altimetric gravity. A second grid that gives sub-ice (si) elevations is also available and can be accessed via @earth_gebcosi[_\ *rru*\ [_\ *reg*\ ]] and is the one displayed above. The following codes for *rr*\ *u* and the optional *reg* are supported (dimensions are listed for pixel-registered grids; gridline-registered grids increment dimensions by one): .. _tbl-earth_gebco: .. table:: GEBCO Earth Relief. An asterisk denotes tiled datasets. ==== ================= === ======= ================================================ Code Dimensions Reg Size Description ==== ================= === ======= ================================================ 01d 360 x 180 g,p 103 KB 1 arc degree global relief (GEBCO 2023 @ 315 km) 30m 720 x 360 g,p 350 KB 30 arc minute global relief (GEBCO 2023 @ 157 km) 20m 1080 x 540 g,p 729 KB 20 arc minute global relief (GEBCO 2023 @ 105 km) 15m 1440 x 720 g,p 1.2 MB 15 arc minute global relief (GEBCO 2023 @ 79 km) 10m 2160 x 1080 g,p 2.7 MB 10 arc minute global relief (GEBCO 2023 @ 52 km) 06m 3600 x 1800 g,p 7.0 MB 6 arc minute global relief (GEBCO 2023 @ 32 km) 05m* 4320 x 2160 g,p 9.9 MB 5 arc minute global relief (GEBCO 2023 @ 26 km) 04m* 5400 x 2700 g,p 15 MB 4 arc minute global relief (GEBCO 2023 @ 21 km) 03m* 7200 x 3600 g,p 26 MB 3 arc minute global relief (GEBCO 2023 @ 16 km) 02m* 10800 x 5400 g,p 57 MB 2 arc minute global relief (GEBCO 2023 @ 11 km) 01m* 21600 x 10800 g,p 208 MB 1 arc minute global relief (GEBCO 2023 @ 1.9 km) 30s* 43200 x 21600 g,p 864 MB 30 arc second global relief (GEBCO 2023 @ 2.6 km) 15s* 86400 x 43200 p 2.6 GB 15 arc second global relief (GEBCO 2023 original) 03s* 432000 x 216000 g 6.8 GB 3 arc second global relief (SRTM3S original) 01s* 1296000 x 432000 g 41 GB 1 arc second global relief (SRTM1S original) ==== ================= === ======= ================================================ See :gmt-docs:`GMT remote dataset usage ` for when resolution codes are optional or required. All of these data will, when downloaded, be placed in your ~/.gmt/server directory, with the earth_gebco files being placed in an ``earth/earth_gebco`` sub-directory, and earth_gebcosi files in an ``earth/earth_gebcosi`` sub-directory. If you do not specify a CPT then the default CPT (the GMT master *geo* CPT) will be used. Technical Information ~~~~~~~~~~~~~~~~~~~~~ As you see, the 30s and lower resolutions are all derivatives of GEBCO's 2023 15 arc second grids (GEBCO_Compilation_Group, 2023). We have downsampled it via Cartesian Gaussian filtering to prevent aliasing while preserving the latitude-dependent resolution in the original 15 arc sec grid. The full (6 sigma) filter-widths are indicated in parenthesis. The 3 and 1 arc second data are the SRTM 1x1 degree tiles from NASA. **Note**: The 3 and 1 arc second grids only extend to latitudes ±60˚ and are only available over land. When these grids are accessed as @earth_gebco_01s or @earth_gebco_03s we will automatically up-sample the relevant @earth_gebco_15s tiles to fill in the missing ocean values. If you just want the original land-only SRTM tiles you may use the special names @srtm_relief_03s or @srtm_relief_01s instead. Almost all grids are available in both gridline- and pixel-registered formats except the original pixel-registered GEBCO 2023 (here called @earth_gebco_15s) and the gridline-registered SRTM tiles. Data References ~~~~~~~~~~~~~~~ #. GEBCO Compilation Group (2023) GEBCO 2023 Grid (https://doi.org/10.5285/f98b053b-0cbc-6c23-e053-6c86abc0af7b) #. SRTMGL3 tiles: [https://lpdaac.usgs.gov/products/srtmgl3v003]. #. SRTMGL1 tiles: [https://lpdaac.usgs.gov/products/srtmgl1v003].