Problems with the use of "plot_grd" function of the module "maps"

[Bohr-niels]

Can the function "plot_grd" plot the area outside the Antarctic region?
I want to plot the Beaufort Sea in the Arctic, but there are some problems with the projection of the map, the right map with a correct projection is like this:

but now using the "plot_grd" I get the map below:

I think it should be the wrong projection setting, but the "plot_grd" function doesn't contain the projection parameter, and in the reference documentation I haven't found the relevant information yet.

[mdtanker]

Hi @Bohr-niels , that is a well timed question! I've just added support for plotting maps of the Arctic/Greenland. This is currently in PR #212, which will be released in the next few weeks, or you can clone the branch mdtanker-patch-3 and install it locally. There should be some instructions for how to do that in the docs. Let me know if you need help.

Currently I only support plotting with either EPSG 3031, South Polar Stereographic (for antarctica, south of -60°), and EPSG 3413, Sea Ice Polar Stereogrpahic (for greenland and the arctic, north of 60°).

The projections for the figures are set with the function utils.set_proj which is called internally in maps.plot_grd. In the branch above, you must tell polartoolkit which of these projections you want to use with the keyword argument hemisphere with a value of "north" or "south", for whichever hemisphere you want.

If your data is already in EPSG 3413, then plot_grd should work if you pass hemisphere="north". If not, you'll need to reproject it, let me know if you need help with that.

[Bohr-niels]

Thanks a lot, @mdtanker. My data is geographic data in LLZ formats, so if I want to use plot_grd to map it, Should I first reproject it to XYZ formats using EPSG 3413? Maybe pygmt tool helps this work?

[mdtanker]

Yeah first reproject it. I use rioxarray to project from lat lon to meters, see here for an example or projecting to EPSG 3031. Should work to just replace 3031 with 3413.

[mdtanker]

Should be closed when #212 is merged.