GSHHG Earth Distance to Shoreline
Geological, geophysical, oceanographic and biological studies may at times need to know how far it is to the nearest coastline. Here, the coastline is the GSHHG coastline used in GMT.
Usage
You access a global distance grid by specifying the special name
@earth_dist[_rru[_reg]]
The following codes for rru and the optional reg are supported (dimensions are listed for pixel-registered grids; gridline-registered grids increment dimensions by one):
Code |
Dimensions |
Reg |
Size |
Description |
---|---|---|---|---|
01d |
360 x 180 |
g,p |
82 KB |
1 arc degree global distance (MSS @ 315 km) |
30m |
720 x 360 |
g,p |
245 KB |
30 arc minute global distance (MSS @ 157 km) |
20m |
1080 x 540 |
g,p |
500 KB |
20 arc minute global distance (MSS @ 105 km) |
15m |
1440 x 720 |
g,p |
840 KB |
15 arc minute global distance (MSS @ 79 km) |
10m |
2160 x 1080 |
g,p |
1.7 MB |
10 arc minute global distance (MSS @ 52 km) |
06m |
3600 x 1800 |
g,p |
4.3 MB |
6 arc minute global distance (MSS @ 32 km) |
05m* |
4320 x 2160 |
g,p |
5.7 MB |
5 arc minute global distance (MSS @ 26 km) |
04m* |
5400 x 2700 |
g,p |
8.5 MB |
4 arc minute global distance (MSS @ 21 km) |
03m* |
7200 x 3600 |
g,p |
15 MB |
3 arc minute global distance (MSS @ 16 km) |
02m* |
10800 x 5400 |
g,p |
26 MB |
2 arc minute global distance (MSS @ 11 km) |
01m* |
21600 x 10800 |
g |
79 MB |
1 arc minute global distance (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_dist files being placed in an earth/earth_dist
sub-directory. If you do not
specify a CPT, the default CPT for this dataset (the GMT master @earth_dist CPT) will be used.
Technical Information
We scale and reformat the original data to take up very little space so that downloads from the servers are as fast as possible. For the distance grid this meant we chose 80 m as the smallest data unit, which is below the uncertainties in the model. Data are scaled and shifted to fit in a short integer grid that is highly compressed by netCDF lossless compression and chunking. The data are reported in meters.