what are the unit and source of topo data in matlab?

I want to use the elevation data from topo.mat in matlab. I need some information about it. 1)What is the unit for the elevation data? and 2)where did matlab get the data?

Answer 1

[Kimberly]

I had the same question as you!

I don't know if you've gotten an answer yet. The mathworks website says, "National Geophysical Data Center, NOAA US Department of Commerce under data announcement 88-MGG-02."

I did a google search, and here is the website with the relevant information: http://www.ngdc.noaa.gov/mgg/global/etopo5.HTML

Answer 2

[Ted Shultz]

As Kimberly said, the "topo" data is from http://www.ngdc.noaa.gov/mgg/global/etopo5.HTML. Their is a newer data set out (https://www.ngdc.noaa.gov/mgg/global/global.html) with better documentation. That data set says the Lat/Lon are WGS 84, and the elevation is meters above MSL for the center of that cell. I assume that is the same for the older data set used in MATLAB as well.

To convert from MSL to ellipsoid height, see this page:

https://www.mathworks.com/help/map/ellipsoid-geoid-and-orthometric-height.html