etopo5 (Mapping Toolbox)

Read data from the ETOPO5 global 5-minute Digital Terrain Model

Syntax

[map,maplegend] = etopo5(scalefactor)
[map,maplegend] = etopo5(scalefactor,latlim,lonlim)

Background

ETOPO5 is a global database of elevations and depths on a regular 5-minute grid. It is a compilation of data from a variety of different sources, including the U.S. Naval Oceanographic Office, U.S. Defense Mapping Agency, U.S. Navy Fleet Numerical Oceanographic Center, Bureau of Mineral Resources, Australia, and the Department of Industrial and Scientific Research, New Zealand. These databases were assembled by Margo Edwards at Washington University, St. Louis, Missouri.

Description

[map,maplegend] = etopo5(scalefactor) reads the data for the entire world, downsampling the data by the scale factor. The result is returned as a regular matrix map and an associated map legend.

[map,maplegend] = etopo5(scalefactor,latlim,lonlim) reads the data for the part of the world within the latitude and longitude limits. The limits must be two-element vectors in units of degrees.

Remarks

Data values are in whole meters, representing the elevation of the center of each cell. Some parts of the world are represented by data with a horizontal resolution as coarse as 1 degree by 1 degree. The vertical resolution varies from 1 meter for Australia and New Zealand to as much as 150 meters for parts of Africa, Asia, and South America. Oceanographic data in areas shallower than 200 meters contain little detail, because of how depth contours were converted to gridded depths.

ETOPO5 is being superseded by the development of a new digital terrain model called TerrainBase. See the tbase external interface function for more information.

The etopo5 function reads the version of the database contained in two text files, etopo5.southern.bat and etopo5.northern.bat. These files are available over the Internet from The MathWorks:

```
ftp://ftp.mathworks.com
```

An overview of the data can be found at the ETOPO5 information page at the U.S. Geological Survey:

http://edcwww.cr.usgs.gov/glis/hyper/guide/etopo5

and from the U.S. National Geophysical Data Center Web page:

http://www.ngdc.noaa.gov/mgg/global/etopo5.HTML

Examples

Read every tenth point in the dataset:

scalefactor = 10;
[map,maplegend] = etopo5(scalefactor);
whos
  Name              Size         Bytes  Class
  map             216x432       746496  double array
  maplegend         1x3             24  double array
  scalefactor       1x1              8  double array
limitm(map,maplegend)
ans =
   -90    90     0   360

Read in data for Korea and Japan at the full resolution:

scalefactor = 1; latlim = [30 45]; lonlim = [115 145];
[map,maplegend] = etopo5(scalefactor,latlim,lonlim);
whos map
  Name      Size         Bytes  Class
  map     180x360       518400  double array

See Also

gtopo30
Read elevation data from GTOPO30

tbase
Read data from the TerrainBase model

usgsdem
Read USGS digital elevation maps

`gtopo30`	Read elevation data from GTOPO30
`tbase`	Read data from the TerrainBase model
`usgsdem`	Read USGS digital elevation maps

References

More information on ETOPO5 can be found in reference [4] located in the Bibliography at the end of this appendix.

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