[MITgcm-support] restart from a pickup file

[Jean-Michel Campin]

Hi Abbas,

You are right, does not work with NetCDF pickup. There is no
real advantages in using MNC for pickup files (since pickup files
are only used by the model itself, it's in fact faster with
binary files), and you could use MNC for all output files
except pickup files that you keep in simple binary format.

Otherwise, restarting a nonhydrostatic model from an hydrostatic
pickup should not cause problems.
Changing resolution with interpolation from coarse to fine 
is more delicate (you don't want to introduce un-physical divergence
which was not there in the 1rst place).

Thanks,
Jean-Michel

On Fri, Mar 27, 2009 at 01:05:13PM -0400, Abbas Dorostkar wrote:
> Thanks very much Jody and Jean-Michel,
> 
> Jean-Michel 's idea works well with data-meta pickup files but not with nc
> files. I get this error if I use nc files (I am using chechpoint_61h version
> of MITgcm):
> (PID.TID 0000.0001) *** ERROR *** NetCDF ERROR:
> (PID.TID 0000.0001) *** ERROR *** MNC ERROR: MNC_CW_RL_R: cannot get netCDF
> id for variable 'phi_nh' in file 'pickup.0000000216.t001.nc'
> 
> Jean-Michel, have you used nc pickup files? The structure of nc pickup files
> are easy to understand in case I want to interpolate from a coarse to a fine
> grid and restart from a pickup file.
> 
> By the way, does that kind of simulation (restart a nonhydrostatic model
> from a hydrostatic result and/or interpolation from a coarse to a fine
> grid), associate with significant error and/or spin up time. Has anybody
> used those techniques before?
> 
> Thanks
> Abbas
> 
> 
> 
> On Thu, Mar 26, 2009 at 7:23 PM, Jean-Michel Campin <jmc at ocean.mit.edu>wrote:
> 
> > Hi Abbas,
> >
> > On Thu, Mar 26, 2009 at 06:32:48PM -0400, Abbas Dorostkar wrote:
> > > Dear all,
> > >
> > > I am trying to simulate the whole internal wave field in a lake.  My
> > initial
> > > simulation was performed for 10 days (270 to 280 Julian Day) in the
> > > hydrostatic version of MITgcm with fine grids.  Performing the same
> > > simulation in the non-hydrostatic mode is impractical as it takes several
> > > months.
> > >
> > > As a first option, I am thinking about running the nonhydrostatic model
> > for
> > > a time span (from 272-274 days) compatible with the response to a
> > particular
> > > wind event (when internal wave activity is visible in the field data). To
> > > initialize the nonhydrostatic model, I restarted it with the pickup file
> > I
> > > got from the hydrostatic simulation on 272 Julian Day. However, I get
> > this
> > > error message:” field phi-NHyd is missing”.  Is it ok if I put zeros for
> > > phi-Nhyd in the pickup file and restart the model?  The structure of the
> > > pickup file (data-meta file) is not easy to understand. Has anybody done
> > > this before?
> >
> > I suggest to try:
> >  pickupStrictlyMatch=.FALSE.,
> > in the 3rd namelist (PARM03) of parameter file "data"
> > (see, e.g., verification/ideal_2D_oce/input/data)
> > This should allow you to restart from an Hydrostatic pickup.
> >
> > Jean-Michel
> >
> > >
> > > As a second option, I want to run the nonhydrostatic model with a
> > > coarse grid for the whole period and then interpolate from that coarse
> > > grid to a finer grid
> > > and restart from a pickup file.  Does anybody have a matlab script or
> > > a subroutine that does this.
> > >
> > >
> > >
> > > Your help is much appreciated.
> > >
> > > Abbas
> >
> > > _______________________________________________
> > > MITgcm-support mailing list
> > > MITgcm-support at mitgcm.org
> > > http://mitgcm.org/mailman/listinfo/mitgcm-support
> >
> > _______________________________________________
> > MITgcm-support mailing list
> > MITgcm-support at mitgcm.org
> > http://mitgcm.org/mailman/listinfo/mitgcm-support
> >
> 
> 
> 
> -- 
> -------------------------
> Abbas Dorostkar, M.Sc (Eng.)
> PhD Student
> Room 444, Ellis Hall
> Dept. of Civil Engineering
> Queen's University
> Kingston, ON, CANADA K7L 3N6

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