Where can I download 1-degree gridded data of the elevation/depth of
the earth's surface?  Ideally, I want a 180 x 360 matrix.  I don't
want a huge file like you'd get with 5-minute or 2-minute data.

Thanks

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Request for Question Clarification by bikerman-ga on 30 Sep 2003 12:02 PDT

Hi,

I found USGS DEMs available for free download that are labeled as
1-degree DEM data.  However, the elevation samples are taken every 3
to 6 arc-seconds.  This corresponds to a scale of 1:250,000.  Is this
what you are looking for?  Or do you  want the elevation samples to be
1 degree apart?  If so, I know the USGS doesn't produce such datasets
(they have 7.5-minute DEM, 30-minute DEM, 1-degree DEM, 7.5-minute
Alaska DEM, and 15-minute Alaska DEM).  Perhaps someone else has
downsampled the data in a GIS application, but you will almost
certainly have to pay for the service, if it exists at all.

If you have GIS software, you could download the 1-degree DEMs and
resample them to whatever you wanted.  For example in the free GRASS
GIS software (http://grass.itc.it/index.html), you could set the
region to 1 degree by 1 degree (using g.region) and resample the data
with r.resample.

If you are interested in the 1-degree DEM data, I will post an answer
pointing you to where you can download it.  Note also that this data
is only available for the US.

Thanks!
bikerman

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Clarification of Question by racecar-ga on 30 Sep 2003 13:23 PDT

Thanks bikerman.  I wanted to do something in MATLAB, and it actually
turns out that the exact thing I wanted is in a matlab file called
topo.