[MITgcm-devel] Re: [MITgcm-cvs] MITgcm/pkg/diagnostics CVS Commit

[Baylor Fox-Kemper]

Hi Andrea,
   I wasn't suggesting that diagnostics use the transformation 0->  
-1e34.  I was suggesting that we do what we should've been doing all  
along and when we know what values are missing (i.e., when we mask)  
that we set masked values to -1e34.
   If we start out with the default missing value being -1e34, then  
we can, as we find places in the code where we'd like to put in  
missing values, then we can put them in.
   If you have variables where zero really is missing, then the  
substitution is easy.  If you have other variables where its hard,  
say velocity, then you need to do an [if (maskC)] sort of thing.
   If we just put in missing_value=0 it will break everything, but it  
we just put in missing_value=-1e34, it will break nothing and then it  
is up to us to fix missing_values throughout the code when we know  
we've got 'em.
   Cheers,
     -Baylor


On Feb 7, 2006, at 10:25 AM, Andrea Molod wrote:

> hi baylor,
>
>> I suggest that missing value shouldn't be zero by default.  That  
>> just confirms the old problem where masked fields were set to zero  
>> in the masks. For fields like temperature and velocity that was  
>> just a mess.  If we use missing_value=0, and open in ferret or  
>> netcdf, then, for example, in a run started from rest ALL the  
>> initial velocities will be missing!  I suggest the missing value  
>> standard from netcdf:  -1e34.
>
>
> i agree that 0. is a potentially problematic missing value. (i have
> been using 1.e15 in some parts of the code and converting back and  
> forth) but the issue is not only for output files, it is for the  
> model itself (asking the output routines to put -1e34 into the  
> places where the
> field is 0.0 doesn't help much). until we discuss and resolve this, i
> asked ed to add the value we are all using anyway (and is in the  
> fields themselves!) as a netcdf file attribute. i hope that we can  
> leave it
> this way until we deal with (or decide that 0. is ok) it in a somewhat
> consistent manner.
>
> andrea
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