Regridding with ESMF and the stand alone utility
I have created a simple utility that can regrid from Lat-Lon to Cubed-Sphere and vise versa using the ESMF integrated regridding. The utility supports both bilinear, conservative, and 2nd order conservative regridding. It should be able to read any Lat-Lon or Cubed-Sphere file produced by GEOS-5 and regrid to another Lat-Lon or Cubed-Sphere grid and requires no tile files to do the conservative regridding for example and should scale well to handle very large grids.
Limitations:
The data you are regridding can not have missing values. ESMF does now support this and I will work at adding this to my utility. Can not regrid vectors properly, i.e. the U and V components of the wind must be done as scalars.
Because this uses some new developments that are not in the CVS repository for the time being I will keep a git repository with the executable you can run or clone and build yourself. Building it is straightforward.
My executable will be located here:
/discover/swdev/bmauer/packages/Regridding/stable/GEOSagcm/build_dir/bin/Regrid_Util.x
To build it yourself on discover, make a directory for the source, go there, then:
module load other/git git clone /discover/swdev/bmauer/packages/Regridding/stable/GEOSagcm
A GEOSagcm directory will appear in the location you did the clone
cd GEOSagcm source src/g5_modules mkdir build_dir cmake ../src -DBASEDIR=$BASEDIR/Linux -DCMAKE_BUILD_TYPE=Release make -j3 Regrid_Util.x
now in the build_dir under GMAO_Shared/MAPL_Base you will have a Regrid_Util.x you can run, copy, etc ...
To run: This program does require at least 6 cores (and uses that by default), so you will need to get an interactive job or run via a batch job.
the run command is
mpirun -np 6 Regrid_Util.x command_line_options
In your interactive job or in your batch script you must source the g5_modules you (or I if using my executable) built is with before running.
The program uses command line options:
-i input_file
-o output_file
-ogrid output_grid_name (for cubed-sphere name is PE360x2160-CF for c360 grid for example, LL example PC360x181-DC is a 360x181 dateline center pole center grid, if you want a pole edge, dateline edge grid do PE360x181-DE for example)
The rest are optional
The nx and ny you need to change for larger grids, then next step up would be nx=2,ny=12, then nx=4,ny=24, then, nx=6,ny=36, the number of processors for the mpirun command must be nx*ny
-nx nx (default is 1)
-ny ny (default is 6)
-vars var1,var2 (comma separated list of variables to regrid from file if you do not want them all)
-t date time (date and time to select from file if you don't want them all for exmaple 20000415 210000)
-method regrid_method ("bilinear", "conservative", "conservative2" are the choices, bilinear is the default, and conservative 2 is 2nd order conservative
-cubeFormat cube_format (options are "old" or "new", the default is new, this is whether you want the new or old cube-sphere file format is you are regridding to a cubed-sphere grid)