How can I plot polar stereographic projection?
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Hello, I have concentration, latitude and longitude data as [m x n] matrices from NSIDC (<http://nsidc.org/data/docs/daac/nsidc0079_bootstrap_seaice.gd.html)>. The data are gridded over polar stereographic grid. Can someone help me to plot sea ice concentration over the Arctic?
Thanks very much, BD
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Accepted Answer
Chad Greene
on 26 Feb 2016
You'll want to download psn25lats_v3.dat and pss25lats_v3.dat, which contain lat,lon grid information. The seaice function imports lat,lon grids for the southern hemisphere like this:
fid = fopen('pss25lons_v3.dat');
lon = fread(fid,[316 332],'long','ieee-le')/100000;
fclose(fid);
fid = fopen('pss25lats_v3.dat');
lat = fread(fid,[316 332],'long','ieee-le')/100000;
fclose(fid);
You can then use Andrew Bliss' polarstereo_fwd to convert lat,lon to x,y and plot with pcolor or imagesc.
Hope this helps.
3 Comments
Chad Greene
on 1 Mar 2016
What are the values in x and y after they're defined by polarstereo_fwd? They should be on the order of 10^6 meters.
Chad Greene
on 4 May 2016
More Answers (1)
Chad Greene
on 6 Aug 2018
One option is to use Arctic Mapping Tools for Matlab, which includes functions to transform between geo coordinates and polar stereographic coordinates. Also includes many functions such as plotpsn and pcolorpsn which plot lat,lon data in polar stereographic (north) coordinates.
3 Comments
Chad Greene
on 17 Jun 2019
You'll need to turn your vectors into grids, and you can do that with one step. It will probably be either:
[Lat,Lon] = meshgrid(lat,lon);
pcolorpsn(Lat,Lon,Z)
or possibly
[Lon,Lat] = meshgrid(lon,lat);
pcolorps(Lat,Lon,Z);
That should be all you need. If you try one of this and it seems to work except that the results are upside down, you might need to do fliplr(lon) or flipud(lon) or fliplr(lat) or flipud(lat) inside the call to meshgrid.
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