Read 2-minute terrain/bathymetry from Smith and Sandwell
[latgrat,longrat,z] = satbath
[latgrat,longrat,z] = satbath(scalefactor)
[latgrat,longrat,z] = satbath(scalefactor,latlim,lonlim)
[latgrat,longrat,z] = satbath(scalefactor,latlim,lonlim,gsize)
[latgrat,longrat,z] = satbath reads
the global topography file for the entire world (
returning every 50th point. The result
is returned as a geolocated data grid. If you use a different version
of the global topography file, you need to rename it to "
If the file is not found on the MATLAB® path, a dialog opens
to request the file.
[latgrat,longrat,z] = satbath(scalefactor) returns
the data for the entire world, subsampled by the integer
scalefactor of 10 returns every 10th point. The
matrix at full resolution has 6336 by 10800 points.
[latgrat,longrat,z] = satbath(scalefactor,latlim,lonlim) returns
data for the specified region. The returned data extends slightly
beyond the requested area. If omitted, the entire area covered by
the data file is returned. The limits are two-element vectors in units
of degrees, with
latlim in the range
lonlim in the range
[latgrat,longrat,z] = satbath(scalefactor,latlim,lonlim,gsize) controls
the size of the graticule matrices.
gsize is a
two-element vector containing the number of rows and columns desired.
If omitted, a graticule the size of the data grid is returned.
This is a global bathymetric model derived from ship soundings and satellite altimetry by W.H.F. Smith and D.T. Sandwell. The model was developed by iteratively adjusting gravity anomaly data from Geosat and ERS-1 against historical track line soundings. This technique takes advantage of the fact that gravity mirrors the large variations in the ocean floor as small variations in the height of the ocean's surface. The computational procedure uses the ship track line data to calibrate the scaling between the observed surface undulations and the inferred bathymetry. Land elevations are reduced-resolution versions of GTOPO30 data.
Read the data for the Falklands Islands (Islas Malvinas) at full resolution.
[latgrat,longrat,mat] = satbath(1,[-55 -50],[-65 -55]); whos Name Size Bytes Class latgrat 247x301 594776 double array longrat 247x301 594776 double array mat 247x301 594776 double array
Land elevations are given in meters above mean sea level. The data is stored in a Mercator projection grid. As a result, spatial resolution varies with latitude. The grid spacing is 2 minutes (about 4 kilometers) at the equator.
This data is available over the Internet, but subject to copyright. The data file is binary, and should be transferred with no line-ending conversion or byte swapping. This function carries out any byte swapping that might be required. The data requires about 133 MB uncompressed.
The data and documentation are available over the Internet via
http and anonymous ftp. Download the latest version of file
x is the version number, and rename it
compatibility with the
satbath returns a geolocated data grid
rather than a regular data grid and a referencing vector or matrix.
This is because the data is in a Mercator projection, with columns
evenly spaced in longitude, but with decreasing spacing for rows at
higher latitudes. Referencing vectors and matrices assume that the
number of cells per degrees of latitude and longitude are both constant
across a data grid.
Note For details on locating map data for download over the Internet, see the following documentation at the MathWorks Web site: Finding Geospatial Data.