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Subsections

7.7.4 Technical details

7.7.4.1 File name

A file name is formed by three parameters which need to be set up as global variables in Matlab before running any routines. They are:
  • the prefix, ie the variable name (netcdf_UVEL for example). This parameter is specified in the help section of all diagnostic routines.
  • netcdf_domain: the geographical domain.
  • netcdf_suff: the netcdf extension (nc or cdf for example).
Then, for example, if the calling Matlab routine had set up: 
global netcdf_THETA netcdf_SALTanom netcdf_domain netcdf_suff
netcdf_THETA    = 'THETA';
netcdf_SALTanom = 'SALT';
netcdf_domain   = 'north_atlantic';
netcdf_suff     = 'nc';
the routine A_compute_potential_density.m to compute the potential density field, will look for the files: 
THETA.north_atlantic.nc
SALT.north_atlantic.nc
and the output file will automatically be: SIGMATHETA.north_atlantic.nc.

Otherwise indicated, output file prefix cannot be changed.

7.7.4.2 Path to file

All diagnostic routines look for input files in a subdirectory (relative to the Matlab routine directory) called ./netcdf-files which in turn, is supposed to contain subdirectories for each set of fields. For example, computing the potential density for the timestep 12H00 02/03/2005 will require a subdirectory with the potential temperature and salinity files like: 
./netcdf-files/200501031200/THETA.north_atlantic.nc
./netcdf-files/200501031200/SALT.north_atlantic.nc
The output file SIGMATHETA.north_atlantic.nc will be created in ./netcdf-files/200501031200/. All diagnostic routines take as argument the name of the timestep subdirectory into ./netcdf-files.

7.7.4.3 Grids

With MITgcm numerical outputs, velocity and tracer fields may not be defined on the same grid. Usually, UVEL and VVEL are defined on a C-grid but when interpolated from a cube-sphere simulation they are defined on a A-grid. When it is needed, routines allow to set up a global variable which define the grid to use.

next up previous contents
Next: 7.7.5 Notes on the Up: 7.7 Potential vorticity Matlab Previous: 7.7.3 Key routines   Contents
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