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Restart options

Restart files

Accuracy: The restart files store data in double precision (precision used in the code). They store transported tracers, air mass and pressure fields. When cutting a run into two or more chunks, using restart file gives the same results as a run done in one go. However, this restartibility is currently broken in some configuration, see #549.

Flexibility: The restart files are tied to a date and a resolution, and consequently their file name follow the TM5_restart_YYYYMMDD_HHMM<region-name>.nc_ format. However, they can be used for a different start date and/or resolution and/or met fields driver (ei, od, ec-earth). You just need to rename the restart file with the correct date and resolution, and set istart=32 in your rc file. Since 2018-02-20, the restart files can be read/written with a netcdf4 library without parallel IO support. If you add tracers to the simulation, you can still use restart files, again with istart=32: the missing tracers will be filled with a default very small value (see code).

Rc file settings

Settings for the initial state of the atmospheric tracers are found in the "Restart files" section of the main rc file. The section also deals with the restart files being written by the run.

   1  !=====================================================================!
   2  ! Restart files
   3  !=====================================================================!
   4  ! initial fields
   5  istart              : 33
   6  ! Directory (case of istart=33 or 32)
   7  restart.read.dir    : /path/to/TM56_input/testdata_restart/
   8  ! File (case of istart=4, 30, 31, 5)
   9  start.31.glb300x200 : /path/to/TM56_input/testdata_restart/m7_save_2007010100_glb300x200.hdf
  10   
  11  restart.write                 :  T
  12  ! extra restart files
  13  restart.write.extra           :  F
  14  restart.write.extra.hour      :  00
  15  restart.write.extra.dhour     :  24
  16  ! where to write restart files:
  17  restart.write.dir             :  ${my.run.dir}/restart
  18  ! ensure creation of directory;
  19  restart.install.dir           :  ${restart.write.dir}

line 5: the istart key defines how the tracers are set at the beginning of a run. Possible values are:

1 initial fields set to 0.
2 initial fields computed in sources_sinks/trace1, currently a very tiny non-zero value
32 read from restart file (only tracers mass). Allows remapping, different start date, and missing tracers
33 read from restart file
4 with initial fields read from model output stored in mixing ratio (no slopes), in a so-called "saveoldfile".
5 with initial fields (transported only) read from an mmix output file in mixing ratio (no slopes, missing field set to zero)
9 user defined in module 'user_input'

line 7: only used if istart=33 or 32. Indicates the directory where to find the restart file to read for the first chunk of your run. Other restart files written at the end of a run can be somewhere else, see line 17.

line 9: only used if istart=4, 30, 31, or 5. In which case the key provides the fully qualified name of the file to read. Note that some istart options require a specific format for the file name.

line 11: if set to T (true), then restart files are written at the end of each chunks. If false, then save files are written instead. Soon to be obsolete.

line 13-15: you can have restart file written at time step(s) other than the end of the run. Set restart.write.extra to T to have additional restart files every restart.write.extra.dhour, and at the restart.write.extra.hour hour. The later, if set to 00, is useful to create a restart file from a mmix file or another restart file tied to a different date.

line 17: specifies the directory where restart or save files are written.

line 19: leave this key as is. It is used to create the restart directory if missing.