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Changing wrfout's coordinates to latitude-longitude


New member
I'm using the WRF model to produce meteorological input for the chemical transport model EMEP, which I use to produce data on PM2.5 concentrations in Denmark.
I premise that, since I'm an economist, I have very little knowledge about this kind of models and I apologize in advance if my questions will be trivial.
I noticed that, although I'm using the option map_proj = 'lat-lon', the wrfout coordinates are not in latitude-longitude format but in a different one. Since the EMEP output has the same grid as the meteorological input, also my final output has these coordinates.
What I would like to do is to merge my output to a dataset containing some characteristics of Danish municipalities. However, since the latter dataset only has latitude-longitude coordinates, I'm struggling to perform this merge. I noticed that, in the output file, there are latitude and longitude as separate variables, but since they are not "aligned" (i.e. they don't let me split my grid in rectangles using for example the R function "raster"), the merge is still really challenging.

Therefore, my questions are the following:
1) Is there a way to produce wrfout files with coordinates in "standard" (again, I apologize for the lack of technical language) latitude-longitude format?
2) Alternatively, do you know how to merge a dataset with latitude-longitude coordinates? In particular, I'm currently using R and, in the Danish dataset I have, for each municipality, a multipolygon object containing the points corresponding to the municipality boundaries. I would like to use the "extract" function to merge the PM2.5 concentrations from my EMEP output files.

Thank you so much in advance!
Hi Lorenzo,
To address your first question, there isn't a WRF run-time option that allows outputting in lat/lon coordinates, but you can address this during post-processing. I believe it's possible using NCL. Note, there is also an NCL section on this forum - you may get lucky and find another post related to this topic in that section - not sure, but it's worth a try. You may also find something online, in general, about it. You may also find this presentation on NCL to be useful.

Unfortunately I'm not sure about the second question, but it's possible someone else on the forum may see your question and have some advice!