[MITgcm-support] query ?

[Martin Losch]

Amitabh,
the problem is fairly simple to diagnose: When you change the  
topography you make a few grid cells "wet" that have been "dry" with  
the default topography (which is, BTW, derived from etopo5, you also  
probably have now dry cells that were wet with the default topography,  
but they don't cause these problems). The initial temperature and  
salinity fields (lev_t.bin and lev_s.bin) are derived (from World Ocean  
Atlas 1994, Levitus etal) by interpolating them according to the  
default bathymetry, so in these formerly dry cells that are wet with  
your bathymetry, you have zeros for temperature and salinity. These  
values cause the program to stop.
You have two choices:
1. comment out the appropriate lines in model/src/ini_theta.F and  
ini_salt.F, but this will only lead to vigorous adjustment processes  
that will cause the model to blow up unless you choose a very small  
timestep. So don't do that.
2. interpolate (potential) temperature and salinity so there are  
non-zero values everywhere. It's completely up to you to do that. I  
usually define the bathymetry and layerthicknesses, run the model once  
until it stops with the same error messages that you get and then I use  
the information in hFacC.001.001.data/meta (or grid.000001.nc if you  
are using the netcdf interface) to do the interpolation. hFacC is the  
3D-landmask variable, it is 0 for a dry cell, 1 for a wet cell and  
between 0 and 1 for a partial/looped cell (which you could treat as 1  
for interpolation for a start, although not accurate).

hope that helps,
Martin


On Feb 15, 2005, at 10:48 AM, Amitabh Mitra wrote:

>   
>  Dear Sir,
>
>  I have successfully run the inbuilt experiment
>  global_ocean.90x40x15. Then I extracted topography
>  data from Etopo2.raw.bin for the region below
>
>  Latitude 80 S to 76 N Longitude 4 E to 360 E
>  for 4 by 4 degree resolution.
>
>  The number of bytes for the extracted data matches
>  with the original bathymetry.bin (i.e 14400) please see
>  attachment.
>
>  To check the validity ,I apply this extracted data in
>  place of original bathymetry.bin but an error message
>  is displayed as I execute the model as shown below :-
>
>  SGI_2100 25% mpirun -np 1 ./mitgcmuv
>  S/R INI_THETA: theta = 0 identically. If this is intentionalyou will  
> need to edit
>  ini_theta.F to avoid this safety check
>  STOP ABNORMAL END: S/R INI_THETA
>  STOP
>  MPI: MPI_COMM_WORLD rank 0 has terminated without calling  
> MPI_Finalize()
>
>   
> -----------------------------------------------------------------------
>  I suppose I have to extract each data, as required by the
>  experiment, only bathymetry.bin will not work, or maybe some
>  thing is wrong with my extracted data.
>  What could be the problem ?
>
>  Regards,
>
>  Amitabh Mitra
>
>
>   
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