Issue with Missing 'U' Field After Regridding fv09 Initial File

[Will Smith]

Hi all,

I intend to regrid an fv09 Cam-Chem_ic_nudge.cam.i.2010-01-08-00000.nc file onto a SE grid. There were no errors shown in the log file during the regridding process. However, when I use it as the ncdata to run CESM2.2, I meet the following error in both the atm.log and cesm.log files:

ERROR: DYN_FIELD_EXISTS: U was not present in the input file

I checked the data before and after regridding, and it seems that the wind-related variables have disappeared in the regridded file.

Below is the code I used. Could you please advise where the issue might be?

module load use.own
module load esmf/8.6.1
module load libs/gcc/nco/4.8.1

export srcgrid=f09
export dstgrid=ne0np4.UK_ne30x16
export srcgridfile="/mnt/iusers01/fatpou01/sees01/s29826zs/scratch/MUSICARE/ne0np4.UK_ne30x16/inic/fv0.9x1.25_141008.nc"
export dstgridfile="/mnt/iusers01/fatpou01/sees01/s29826zs/scratch/MUSICARE/ne0np4.UK_ne30x16/grids/UK_ne30x16_np4_SCRIP.nc"

export srcinitfile="/mnt/iusers01/fatpou01/sees01/s29826zs/scratch/Projects/archive/2.2project/cam-chem_ic_nudge/atm/hist/cam-chem_ic_nudge.cam.i.2010-01-08-00000.nc"
export dstinitfile="/mnt/iusers01/fatpou01/sees01/s29826zs/scratch/MUSICARE/ne0np4.UK_ne30x16/inic/test.nc"

ESMF_RegridWeightGen --ignore_unmapped --method conserve --weight map_${srcgrid}_to_${dstgrid}.nc --source ${srcgridfile} --destination ${dstgridfile}

ncremap -m ./map_${srcgrid}_to_${dstgrid}.nc -i ${srcinitfile} -o ${dstinitfile}

Many thanks

 

[hplin]

Hi Will Smith,

I am not sure why ncremap is not regridding the wind fields. Could you try running ncremap with the -v option to just regrid the wind-related variables (e.g., `ncremap -v U,V`) to see if maybe there are more detailed logs or if that can succeed?

Alternatively, in the CAM-chem / MUSICA wiki there are a collection of regridding tools that I previously used to regrid CAM-chem initial condition files from the FV to the SE grid: Input Processing Tools - MUSICA - wiki.ucar.edu - I checked and my outputs from that (which I believe should also be using ESMF for regridding, via NCL) did have the wind fields. So if it is possible I would also suggest trying to use the scripts from there (IPT/Initial_conditions/regrid_all_spectral_data.ncl at master · NCAR/IPT is what I used).

 

[Will Smith]

Hi Will Smith,

I am not sure why ncremap is not regridding the wind fields. Could you try running ncremap with the -v option to just regrid the wind-related variables (e.g., `ncremap -v U,V`) to see if maybe there are more detailed logs or if that can succeed?

Alternatively, in the CAM-chem / MUSICA wiki there are a collection of regridding tools that I previously used to regrid CAM-chem initial condition files from the FV to the SE grid: Input Processing Tools - MUSICA - wiki.ucar.edu - I checked and my outputs from that (which I believe should also be using ESMF for regridding, via NCL) did have the wind fields. So if it is possible I would also suggest trying to use the scripts from there (IPT/Initial_conditions/regrid_all_spectral_data.ncl at master · NCAR/IPT is what I used).

Hi Lin,
Thank you very much for your reply.
I’ve tried regridding only the wind-related variables using ncremap -v, but unfortunately, the resulting regridded file still does not contain these variables.

From what I can tell, the wind fields in the CAM-Chem (FV grid) initial condition files are stored as US and VS, for example:

double US(time, lev, slat, lon) ;
US:mdims = 1 ;
US:units = "m/s" ;
US:long_name = "Zonal wind, staggered" ;

Whereas in MUSICA (SE grid), the winds appear as U and V, such as:

double U(time, lev, ncol) ;
U:long_name = "Zonal wind" ;
U:units = "m/s" ;
U:mdims = 1 ;
U:_FillValue = 9.96920996838687e+36 ;

This discrepancy in variable names and grid staggering may be why ncremap isn’t handling the conversion as expected, though I’m still not entirely certain.

Regarding the IPT scripts you mentioned: I’ve previously used them successfully for SE-to-SE regridding of initial conditions. Are you saying they also support FV-to-SE regridding?

Many thanks again for your suggestions!

 

[hplin]

Sorry, you're right, I likely had my scripts mixed up. I vaguely remember that I did some regridding (a long time ago...) between f09 and ne30 but maybe it was not through IPT (so I am not sure if IPT will be able to do FV-to-SE regridding); I might have done the regridding for the chemical tracers only, then combined that information into a ne30 initial conditions file (spun up separately) which had the SE winds.

I will move this thread to the CAM-chem forum for more visibility from the chemistry folks, who may have a more accurate answer as to how to regrid FV initial conditions for use on the SE grid. Thanks!