[MITgcm-support] Problem with Bathymetry

[Martin Losch]

Abbas,

it's not clear (to me) what you are trying to do. A general procedure  
for generating a new model domain (regardless of ocean/marginal sea/ 
lake) would be:
1. define the grid: a. number of grid points: set Nx,Ny (via  
sNx*nSx*pNx etc in SIZE.h), b. grid spacing (via delX/Y or dX/ 
Yspacing and choice of coordinate systems in "data"/PARM04)
2. create bathymetry file. This file needs the same number of grid  
points as defined in SIZE.h (Nx,Ny); the vertical axis is positive  
upwards, that is, negative values describe topography below sea  
level. Positive values are interpreted as land. The file needs to be  
IEEE big endian, unblocked, fortran-unformated, direct access file,  
with matlab this is easy:
h=-1000*ones(nx,ny);
fid=fopen('bathy.file','r','b'); fwrite(fid,h,'real*4'); fclose(fid);
for a constant depth of 1000m, saved as single precision (then you  
need to set readbinaryprec=32 in data)

Does that help?

Martin

On 7 Nov 2008, at 00:05, Abbas Dorostkar wrote:

> Dear all,
>
>
>
> To generate the bathymetry file of a lake, I interpolate the lake  
> topography to the grid coordinates, using the correct size  
> corresponding to the model domain size set in SIZE.h .  However,  
> when values of nx and ny are not large enough, the bathymetry does  
> not look very good.
>
> I increased these values in the bathymetry file but not in SIZE.h  
> and data namelist (delx and dely). The model returns zero values  
> for velocities and temp without blowing up.  I am assuming the  
> values of nx and ny should be the same in both SIZE.h and  
> bathymetry file. Is that right?
>
> I am thinking to tune the bathymetry manually (by-hand adjustment).  
> Is there any other way to address this issue.
>
>
>
> Thanks so much
>
> Abbas
>
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