Hello, Here is hoping my question is on topic :-) I downloaded NCEP reanalysis data from a THREDDS server and my dimensions are the following - time(record dimension), lat,lon,level When I do a nf_inq_var it turns out lat and lon are 1D arrays. I then transformed my global coordinates of NCEP into what is known as rotated lat lon grid(common in mesoscale modeling such as WRF, etc) https://github.com/thiasB/unrotMe/blob/master/geo2rot.f90 using the two subroutines - phi2phirot and rla2rlarot. I now have the rotated latitude and longitude but these are now two dimensional arrays. That is for each global latitude and longitude I have a rotated latitude. And similarly for a rotated longitude. How do I write this rotated lat and lon back to the netCDF file given the fact that dimensions are different ? What I mean by that is I want to replace the original lat and lon of the geographical system with the rotated lat and lon of the rotated coordinate system. I am guessing I will have to create a new netCDF file and copy all the other information over to that file. Or is there a way to make the edits to the original file itself ? Any other alternatives will be deeply appreciated. Regards, Ashwin.