IGPP Earth Relief

Usage

You access a global relief grid by specifying the special name

@earth_relief[_rru[_reg]]

This grid only contains observed relief and inferred relief via altimetric gravity. A new version that uses the statistical properties of young seafloor fabric and directions of spreading is also available and provides more realistic relief in areas of young seafloor with small seamounts. That grid can be accessed via

@earth_synbath[_rru[_reg]]

The following codes for the optional rru and reg are supported (dimensions are listed for pixel-registered grids; gridline-registered grids increment dimensions by one):

IGPP Earth Relief. An asterisk denotes tiled datasets.

Code	Dimensions	Reg	Size	Description
01d	360 x 180	g,p	111 KB	1 arc degree global relief (SRTM15+V2.5.5 @ 315 km)
30m	720 x 360	g,p	381 KB	30 arc minute global relief (SRTM15+V2.5.5 @ 157 km)
20m	1080 x 540	g,p	799 KB	20 arc minute global relief (SRTM15+V2.5.5 @ 105 km)
15m	1440 x 720	g,p	1.3 MB	15 arc minute global relief (SRTM15+V2.5.5 @ 79 km)
10m	2160 x 1080	g,p	2.9 MB	10 arc minute global relief (SRTM15+V2.5.5 @ 52 km)
06m	3600 x 1800	g,p	7.7 MB	6 arc minute global relief (SRTM15+V2.5.5 @ 32 km)
05m*	4320 x 2160	g,p	11 MB	5 arc minute global relief (SRTM15+V2.5.5 @ 26 km)
04m*	5400 x 2700	g,p	17 MB	4 arc minute global relief (SRTM15+V2.5.5 @ 21 km)
03m*	7200 x 3600	g,p	30 MB	3 arc minute global relief (SRTM15+V2.5.5 @ 16 km)
02m*	10800 x 5400	g,p	63 MB	2 arc minute global relief (SRTM15+V2.5.5 @ 11 km)
01m*	21600 x 10800	g,p	233 MB	1 arc minute global relief (SRTM15+V2.5.5 @ 1.9 km)
30s*	43200 x 21600	g,p	854 MB	30 arc second global relief (SRTM15+V2.5.5 @ 2.6 km)
15s*	86400 x 43200	p	2.9 GB	15 arc second global relief (SRTM15+V2.5.5 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 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_relief files being placed in an earth/earth_relief sub-directory and the earth_synbath files in an earth/earth_synbath sub-directory. If you do not specify a CPT then the default CPT for this dataset (the GMT master geo CPT) will be used.

Technical Information

As you see, the 30s and lower resolutions are all derivatives of Scripps’ SRTM15+V2.5.5 grid (Tozer et al., 2019). 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_relief_01s or @earth_relief_03s we will automatically up-sample the relevant @earth_relief_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 SRTM15+V2.5.5 (here called @earth_relief_15s) and the gridline-registered SRTM tiles.

Data References

1. SRTM15+V2.5.5: [https://doi.org/10.1029/2019EA000658].

2. SYNBATH_V2.0: [https://doi.org/10.1029/2021EA002069].

3. SRTMGL3 tiles: [https://lpdaac.usgs.gov/products/srtmgl3v003].

4. SRTMGL1 tiles: [https://lpdaac.usgs.gov/products/srtmgl1v003].