History files contain gridded data values written at specified times
during a model run. By default, the history files will be written to
the directory history_dir defined in the namelist.
The netCDF file names are prepended by the character
string given by history_file in the ice_nml namelist.
This character string has been set according to CESM Output Filename Requirements.
If history_file is not set in the namelist, the default character string
'iceh' is used. The user can specify the frequency at which the data
are written. Options are also available to record averaged or instantaneous data.
The form of the history file names are as follows:
Yearly averaged: $CASE.cice.h?.yyyy.nc
Monthly averaged: $CASE.cice.h?.yyyy-mm.nc
Daily averaged: $CASE.cice.h?.yyyy-mm-dd.nc
Instantaneous (histfreq = 'y', 'm', or 'd'): $CASE.cice.h?_inst.yyyy-mm-dd-sssss.nc
Instantaneous (written every dt, histfreq = 1): $CASE.cice.h?_inst.yyyy-mm-dd-sssss.nc
$CASE is set in the main setup script. Note that the ? denotes the multiple stream option where the first stream is just .h. and subsequent streams are h1, h2, etc. All history files are written in the executable directory. Changes to the frequency and averaging will affect all output fields. The best description of the history data comes from the file itself using the netCDF command ncdump -h filename.nc. Variables containing grid information are written to every file and are listed in Table 8. In addition to the history files, a netCDF file containing a snapshot of the initial ice state can be created at the start of each run. The file name is $CASE.cice.i.yyyy-mm-dd-sssss.nc and is written in the executable directory.