How do I remap and merge GFDL-AM4 output files

[ZHONGLEI-sketch]

Now I have INPUT/C96_mosaic.nc and 19790101.grid_spec.tile1.nc.0000 19790101.grid_spec.tile1.nc.0001 etc. And the corresponding 19790101.atmos_daily.tile1.nc.0000 19790101.atmos_daily.tile1.nc.0001 etc. thank you.

[ceblanton]

Hello, sorry for the delay. You're asking how to combine/merge the decomposed FMS history files, and then how to regrid from the cubed-sphere grid to a standard lat-lon grid.

To merge/combine the decomposed FMS history files, use mppnccombine, specifying the output file first, followed by the input files. e.g.

mppnccombine 19790101.grid_spec.tile1.nc 19790101.grid_spec.tile1.nc.????
mppnccombine 19790101.atmos_daily.tile1.nc 19790101.atmos_daily.tile1.nc.????

Then, to regrid to a standard lat-lon grid, use fregrid. You will need the FMS grid mosaic definition file for your input grid, decide which input variables to regrid, your target lat-lon resolution, and which regridding algorithm to use (typically conserve_order2 or conserve_order1. e.g. to regrid thetas` variable using 2nd order conservation to a 360x180 1-degree output grid:

fregrid --standard_dimension --input_mosaic C96_mosaic.nc --input_file 19790101.atmos_daily --interp_method conserve_order2 --nlon 360 --nlat 180 --scalar_field tas --output_file out.nc

Hope this helps!