GSHHG Earth Distance to Shoreline

_images/GMT_earth_dist.jpg

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)

Note that resolutions 05m and higher are tiled. See Remote Data Sets for more information.

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.

Data References

  1. https://doi.org/10.5670/oceanog.2010.32.

  2. https://doi.org/10.2478/s11600-010-0038-1.