Read Global Topographic Data
29 Apr 2008
07 May 2008)
Two Matlab functions to extract the data from two global topographic data base, ETOPO2v2 and GEOBEC.
|[LON LAT HH]=read_etopo2v2g_f4_nc_v2
function [LON LAT HH]=read_etopo2v2g_f4_nc_v2
% Read ETOPO2v2g data
%% Note: The original data comes such that LON(end)==LON(1)+360 is true.
% This means that HH(:,1) and HH(:, end) actually describe the
% topographic data on the same meridian line. We therefore expect
% that HH(:,1)==H(:,end) should be true. However this is not the case.
% If you uncommend and evaluate the following two lines,
% you will find that out of the total 5401 points along the same meridian
% line, HH(:,1) and HH(:, end) disagree for 4774 points, with differences
% ranging from 1 m to 2328 m. I am puzzled why the ETOPO2 fellows did not
% bother to check out this problem. In this regard, GEOBEC data is much
% better; I find only two points there different, with 1 m difference
% (see my notes in read_GridOne_v2).
%% However, we need to discard one of the repetitive mericiand lines anyway.
%% ETOPO2v2g_f4.nc can be downloaded from