I have spatial data from the WRF-model. I don't know what kind of projection was used to produce these data (neither longitude nor latitude are constant at any borders), but I have 2D matrixes for each longitude and latitude. The area covered is North America. How can I add a map using these 2D matrixes?
The easiest way is to find out what the actual projection is, and
reconstruct a sensible representation of the grid.
Usually you have to guess, but it's possible to figure out. You *can* plot
by building a proper mesh in longlat, but my preference is full rescue. You
need to know the projection and its particulars, i.e. google suggests its
Lambert Conformal Conic but you also need datum/ellipsoid, standard
parallels, and central longitude/latitude at a minimum.
If you can point to an actual example and some trail of where it came from
someone could help.
Also, R-Sig-Geo is a specialized mailing list for this stuff.