Ocean Gotchas

1)  Hybrid or branch simulations,  MUST have an ocean header file (.hdr) with the same name as the restart file.  Simulations that are missing the header file will give a warning message ("... missing hdr file...") but will appear to run.  They will usually fail, however, within a few days. 


  • myrun.pop.r.0801-01-01-00000.ZeroV.110322.hdr (ASCII header file)
  • myrun.pop.r.0801-01-01-00000.ZeroV.110322 (binary restart file)


2)  POP2 grid and KMT files must be in big-endian format, regardless of the native format of the machine on which you are running CESM.

3)  When ocean history files are viewed using ncview, the year appears to be one year greater than the filename indicates.  e.g., year 896-01 will appear be displayed as year 897-01 in ncview.

4)  IAGE bug 

The non-standard initialization of TEMP & SALT is not compatible with CESM's restart script mechanisms. Despite CONTINUE_RUN being TRUE in env_run.xml, the model tries to initialize TEMP & SALT with the same IC as was used in the first submission. On restart, the IAGE initialization is trying to read from the same file that TEMP & SALT are being read from, but IAGE is not in that file. This leads to the problem that you are seeing

Solution: Modify user_nl_pop2:   init_ts_option = 'ccsm_continue'   Make this modification when you are restarting after the initial submission.

4)  Namelist parameters:

overflows_on = .false.
overflows_interactive = .false.

init_ts_file = '/glade/p/cesm/palwg/paleo_setup/ocn/ic/ts_init_b20.681_1100-01_s_35.60level.dat'
init_ts_option = 'mean'

lhoriz_varying_bckgrnd = .false.
ldiag_velocity = .false.
ltidal_mixing = .false.

lhoriz_varying_bckgrnd, ldiag_velocity, overflows and tidal mixing all are geographically dependent and so present-day setups are not appropriate if the paleogeography has changed considerably.

The new background vertical velocity parameters were determined by Gokhan and Christine to increase Kappa-v in the deeper ocean in absence of tidal mixing. The tidal mixing normally would do this.