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Update meta-data for the earth_relief_xxy grids (#1846)
* Update meta-data for the earth_relief_xxy grids Since they are now all based on Tozer et al, 2019 using Cartesian filtering then we need to update the attributions. * Also update the RST file
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‎doc/rst/source/datasets/earth_relief.rst‎

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@@ -12,85 +12,85 @@ are ways to control how much is downloaded (see below).
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Usage
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-----
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We have processed and reformatted various publicly available global relief
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We have processed and reformatted publicly available global relief
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grids and standardized their file names. In GMT, you may access a global relief grid
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(or a subset only by using the **-R** option) by specifying the special name
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@earth_relief_\ *rr*\ *u*
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where *rr* is a 2-digit integer specifying the grid resolution in the unit
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*u*, where *u* is either **m** or **s** for arc minute or arc second, respectively.
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where *rr* is a 2-digit integer specifying the grid resolution in the unit *u*, where
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*u* is either **d**, **m** or **s** for arc degree, arc minute or arc second, respectively.
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The following codes for *rr*\ *u* are supported:
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.. _tbl-earth_relief:
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+------+------------------+--------+-----------------------------------------------+
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| Code | Dimensions | Size | Description |
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+======+==================+========+===============================================+
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| 60m | 361 x 181 | 111 KB | 60 arc minute global relief (ETOPO1 @ 111 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 30m | 721 x 361 | 376 KB | 30 arc minute global relief (ETOPO1 @ 55 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 20m | 1081 x 541 | 782 KB | 20 arc minute global relief (ETOPO1 @ 37 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 15m | 1441 x 721 | 1.3 MB | 15 arc minute global relief (ETOPO1 @ 28 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 10m | 2161 x 1081 | 2.8 MB | 10 arc minute global relief (ETOPO1 @ 18 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 06m | 3601 x 1801 | 7.4 MB | 6 arc minute global relief (ETOPO1 @ 10 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 05m | 4321 x 2161 | 11 MB | 5 arc minute global relief (ETOPO1 @ 9 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 04m | 5401 x 2701 | 16 MB | 4 arc minute global relief (ETOPO1 @ 7.5 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 03m | 7201 x 3601 | 27 MB | 3 arc minute global relief (ETOPO1 @ 5.6 km) |
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+------+------------------+--------+-----------------------------------------------+
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| 02m | 10801 x 5401 | 58 MB | 2 arc minute global relief (ETOPO2v2) |
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+------+------------------+--------+-----------------------------------------------+
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| 01m | 21601 x 10801 | 214 MB | 1 arc minute global relief (ETOPO1) |
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+------+------------------+--------+-----------------------------------------------+
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| 30s | 43201 x 21601 | 778 MB | 30 arc second global relief (SRTM30+) |
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+------+------------------+--------+-----------------------------------------------+
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| 15s | 86401 x 43201 | 2.6 GB | 15 arc second global relief (SRTM15+) |
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+------+------------------+--------+-----------------------------------------------+
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| 03s | 432001 x 216001 | 6.8 GB | 3 arc second global relief (SRTM3S) |
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+------+------------------+--------+-----------------------------------------------+
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| 01s | 1296001 x 432001 | 41 GB | 1 arc second global relief (SRTM1S) |
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+------+------------------+--------+-----------------------------------------------+
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+------+------------------+--------+--------------------------------------------------+
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| Code | Dimensions | Size | Description |
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+======+==================+========+==================================================+
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| 01d | 361 x 181 | 106 KB | 1 arc degree global relief (SRTM15+V2 @ 111 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 30m | 721 x 361 | 363 KB | 30 arc minute global relief (SRTM15+V2 @ 55 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 20m | 1081 x 541 | 759 KB | 20 arc minute global relief (SRTM15+V2 @ 37 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 15m | 1441 x 721 | 1.3 MB | 15 arc minute global relief (SRTM15+V2 @ 28 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 10m | 2161 x 1081 | 2.8 MB | 10 arc minute global relief (SRTM15+V2 @ 18 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 06m | 3601 x 1801 | 7.3 MB | 6 arc minute global relief (SRTM15+V2 @ 10 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 05m | 4321 x 2161 | 10 MB | 5 arc minute global relief (SRTM15+V2 @ 9 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 04m | 5401 x 2701 | 16 MB | 4 arc minute global relief (SRTM15+V2 @ 7.5 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 03m | 7201 x 3601 | 27 MB | 3 arc minute global relief (SRTM15+V2 @ 5.6 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 02m | 10801 x 5401 | 58 MB | 2 arc minute global relief (SRTM15+V2 @ 3.7 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 01m | 21601 x 10801 | 214 MB | 1 arc minute global relief (SRTM15+V2 @ 1.9 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 30s | 43201 x 21601 | 765 MB | 30 arc second global relief (SRTM15+V2 @ 0.9 km) |
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+------+------------------+--------+--------------------------------------------------+
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| 15s | 86400 x 43200 | 2.6 GB | 15 arc second global relief (SRTM15+V2) |
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+------+------------------+--------+--------------------------------------------------+
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| 03s | 432001 x 216001 | 6.8 GB | 3 arc second global relief (SRTM3S) |
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+------+------------------+--------+--------------------------------------------------+
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| 01s | 1296001 x 432001 | 41 GB | 1 arc second global relief (SRTM1S) |
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+------+------------------+--------+--------------------------------------------------+
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All of these data will, when downloaded, be placed in your ~/.gmt/server directory, with
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the SRTM data organized in sub-directories srtm1 and srtm3 within the server directory.
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Technical Information
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---------------------
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As you see, the 03m and lower resolutions are all derivatives of NOAA's ETOPO1 grid. We have
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downsampled it via spherical Gaussian filtering to prevent aliasing. The full (6 sigma)
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filter-widths are indicated in parenthesis. For 2 arc minute we use the original ETOPO2v2
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file from NOAA (with ice_surface). The 30 and 15 arc second grids are the global SRTM30+
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and SRTM15+ products from Dave Sandwell (Scripps), while the 3 and 1 arc second data are
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the SRTM 1x1 degree tiles from NASA. When the 15s or lower resolution grids are accessed
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As you see, the 30s and lower resolutions are all derivatives of Scripps' SRTM15+V2 grid
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(Tozer et al., 2019). We have downsampled it via Cartesian Gaussian filtering to prevent
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aliasing while preserving the latitude-dependent resolution in the original 15 arc sec grid.
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The full (6 sigma) filter-widths are indicated in parenthesis. The 3 and 1 arc second data
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are the SRTM 1x1 degree tiles from NASA. When the 15s or lower resolution grids are accessed
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the first time we download the entire file, regardless of your selected region (**-R**).
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However, for the SRTM tiles we only download the tiles that are inside your selected region
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the first time they are referenced. Also note that the 3 and 1 arc second grids only extend
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to latitudes ±60˚. The SRTM tiles are only valid over land. However, when these grids
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are accessed as @earth_relief_01s or @earth_relief_03s we will automatically upsample the
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@earth_relief_15s grid to fill in the missing ocean values (but only if the region includes oceanic areas).
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If you just want the original land-only
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SRTM tiles you may use @srtm_relief_03s or @srtm_relief_01s instead. All grids are gridline-registered.
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to latitudes ±60˚. The SRTM tiles are only valid over land. However, when these grids are
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accessed as @earth_relief_01s or @earth_relief_03s we will automatically upsample the
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@earth_relief_15s grid to fill in the missing ocean values (but only if the region includes
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oceanic areas). If you just want the original land-only SRTM tiles you may use @srtm_relief_03s
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or @srtm_relief_01s instead. All grids are gridline-registered except the original SRTM15+V2,
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here called @earth_relief_15s.
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The dimensions above reflect the number of nodes covered by the global grids and the sizes are
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the file sizes of the netCDF-4 compressed short int grids, making the files much smaller
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than their original source files without any loss of precision. To improve download speed,
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the SRTM tiles are stored as JPEG2000 images on the GMT server due to superior compression,
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but once downloaded to your server directory they are converted to short int compressed netCDF4 grids.
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This step uses our GDAL bridge and thus requires that you have built GMT with GDAL support
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but once downloaded to your server directory they are converted to short int compressed netCDF4
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grids. This step uses our GDAL bridge and thus requires that you have built GMT with GDAL support
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*and* that your GDAL distribution was built with openjpeg support.
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Data Space Concerns
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-------------------
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There are several ways you can control the amount of space taken up by your server directory:
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There are several ways you can control the amount of space taken up by your own server directory:
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#. You can set an upper file size limit for download via the GMT default setting
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:ref:`GMT_DATA_SERVER_LIMIT <GMT_DATA_SERVER_LIMIT>`; the default is unlimited.
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Data References
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---------------
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#. ETOPO2v2 [https://dx.doi.org/10.7289/V5J1012Q].
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#. ETOPO1: Amante, C., and B. W. Eakins (2008), ETOPO1 1 arc-minute global relief model: Procedures, data sources and analysisRep., National Geophysical Data Center, Boulder, CO [https://www.ngdc.noaa.gov/mgg/global/relief/ETOPO1/data/ice_surface/grid_registered/netcdf/ETOPO1_Ice_g_gmt4.grd.gz].
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#. SRTM30+: Becker, J. J., et al. (2009), Global Bathymetry and Elevation Data at 30 Arc Seconds Resolution: SRTM30_PLUS, Marine Geodesy, 32, 355–371 [ftp://topex.ucsd.edu/pub/srtm30_plus/topo30/topo30.grd].
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#. SRTM15+: Olson, C. L., J. J. Becker, and D. T. Sandwell (2014), A new global bathymetry map at 15 arcsecond resolution for resolving seafloor fabric: SRTM15_PLUS, in Eos Trans. AGU, edited, pp. Abstract OS34A-03 [ftp://topex.ucsd.edu/pub/srtm15_plus/topo15.grd].
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#. SRTM15+V2 [http://dx.doi.org/10.1029/2019EA000658].
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#. SRTMGL3 tiles: [https://lpdaac.usgs.gov/dataset_discovery/measures/measures_products_table/srtmgl3_v003].
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#. SRTMGL1 tiles: [https://lpdaac.usgs.gov/dataset_discovery/measures/measures_products_table/srtmgl1_v003].

‎src/gmt_remote.h‎

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* Include file for list of data grids available via @earth_relief_*.grd references.
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*
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* Author: Paul Wessel
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* Date: 11-Sept-2017
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* Date: 19-Oct-2019
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* Version: 6 API
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*/
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size_t size; /* File size in bytes */
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};
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#define GMT_N_DATA_INFO_ITEMS 15
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#define GMT_N_DATA_INFO_ITEMS 16
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GMT_LOCAL struct GMT_DATA_INFO gmt_data_info[GMT_N_DATA_INFO_ITEMS] = {
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{"60m", "112K", "Earth Relief at 60x60 arc minutes obtained by Gaussian spherical filtering (111 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"30m", "377K", "Earth Relief at 30x30 arc minutes obtained by Gaussian spherical filtering (55 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"20m", "783K", "Earth Relief at 20x20 arc minutes obtained by Gaussian spherical filtering (37 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"15m", "1.4M", "Earth Relief at 15x15 arc minutes obtained by Gaussian spherical filtering (28 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"10m", "2.9M", "Earth Relief at 10x10 arc minutes obtained by Gaussian spherical filtering (18 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"06m", "7.5M", "Earth Relief at 6x6 arc minutes obtained by Gaussian spherical filtering (10 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"05m", "11M", "Earth Relief at 5x5 arc minutes obtained by Gaussian spherical filtering (9 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"04m", "16M", "Earth Relief at 4x4 arc minutes obtained by Gaussian spherical filtering (7.5 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"03m", "28M", "Earth Relief at 3x3 arc minutes obtained by Gaussian spherical filtering (5.6 km fullwidth) of ETOPO1 (Ice g) [NOAA]"},
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{"02m", "58M", "Earth Relief at 2x2 arc minutes provided by ETOPO2v2g_f4 [NOAA]"},
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{"01m", "214M", "Earth Relief at 1x1 arc minutes provided by ETOPO1 (Ice g) [NOAA]"},
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{"30s", "778M", "Earth Relief at 30x30 arc seconds provided by SRTM30+ [Sandwell/SIO]"},
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{"15s", "2.6G", "Earth Relief at 15x15 arc seconds provided by SRTM15+ [Sandwell/SIO]"},
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{"60m", "106K", "Earth Relief at 60x60 arc minutes obtained by Gaussian Cartesian filtering (111 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"01d", "106K", "Earth Relief at 1x1 arc degrees obtained by Gaussian Cartesian filtering (111 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"30m", "363K", "Earth Relief at 30x30 arc minutes obtained by Gaussian Cartesian filtering (55 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"20m", "759K", "Earth Relief at 20x20 arc minutes obtained by Gaussian Cartesian filtering (37 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"15m", "1.3M", "Earth Relief at 15x15 arc minutes obtained by Gaussian Cartesian filtering (28 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"10m", "2.8M", "Earth Relief at 10x10 arc minutes obtained by Gaussian Cartesian filtering (18 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"06m", "7.3M", "Earth Relief at 6x6 arc minutes obtained by Gaussian Cartesian filtering (10 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"05m", "10M", "Earth Relief at 5x5 arc minutes obtained by Gaussian Cartesian filtering (9 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"04m", "16M", "Earth Relief at 4x4 arc minutes obtained by Gaussian Cartesian filtering (7.5 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"03m", "27M", "Earth Relief at 3x3 arc minutes obtained by Gaussian Cartesian filtering (5.6 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"02m", "58M", "Earth Relief at 2x2 arc minutes obtained by Gaussian Cartesian filtering (3.7 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"01m", "214M", "Earth Relief at 1x1 arc minutes obtained by Gaussian Cartesian filtering (1.9 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"30s", "765M", "Earth Relief at 30x30 arc seconds obtained by Gaussian Cartesian filtering (0.9 km fullwidth) of SRTM15+V2 [Tozer et al., 2019]"},
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{"15s", "2.6G", "Earth Relief at 15x15 arc seconds provided by SRTM15+ [Tozer et al., 2019]"},
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{"03s", "6.8G", "Earth Relief at 3x3 arc seconds tiles provided by SRTMGL3 (land only) [NASA/USGS]"},
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{"01s", "41G", "Earth Relief at 1x1 arc seconds tiles provided by SRTMGL1 (land only) [NASA/USGS]"}
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};

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