[MITgcm-devel] netcdf units in diagnostics pkg

[Martin Losch]

Hi Jean-Michel,
thank you for the clarification, now I think I understand what this  
"counter-mate"-business is about (I had thought that this counter- 
mate, simply counts just as ndiags, and not that it actually  
accumulates a model field).

Do you think it's feasible to include "useFizhi" statements in  
getdiag? or rather set undef according to whether useFizhi is true or  
false (in diagnostics_out)?

Also, something like SI_Thice=Sum( iceHeight*iceMask ) / Sum 
( iceMask ) is undefined over land but also where there is no ice.  
Would it make sense to use the same spval/missing value for land and  
no ice? That could easily be done by set "undef" to the missing_value  
of the current output stream before calling getdiag, and then  
resetting it afterwards to getcon('UNDEF').

What do you think?

Martin
On 22 May 2008, at 22:13, Jean-Michel Campin wrote:

> Hi Martin,
>
> On Thu, May 22, 2008 at 02:52:24PM +0200, Martin Losch wrote:
>> Dear diagnostics-authors,
>>
>> Sorry for bothering you with this, but I would like to understand the
>> logic of the routine body getdiag (diagnostics_utils.F, see below):
>
> Courageous guy !
>
>>
>> The first case (mate=0) happens (according to my observations, not my
>> understanding of the code, which I have to admit I don't understand)
>> whenever diagnostics_fract_fill has been used to fill the diagnostics
>> (e.g. SI_Thick), the second case happens when diagnostics_fill has
>> been used to fill the diagnostics (e.g., SI_Fract). In the first
>> case, any value above "undef" (hardwired to getcon('UNDEF') = 1D15)
>> is reset to "undef", in the second case "undef" is only used if the
>> diagnostics has been filled less than once (=not at all).
>>
>> My questions:
>> 1. In the above example (SI_Fract and SI_Thick), SI_Fract contains
>> zeros where there is no ice (iceMask=0), good!. SI_Thick, which
>> should be iceHeight*iceMask (and should be zero where iceMask=0),
>
> I disagree, at the end we want:
> SI_Thick = Sum( iceHeight*iceMask ) / Sum( iceMask )
>
>> there are values of undef=getcon('UNDEF')=1D15 where there is no ice.
>> Now, whether this is useful or not, I just don't understand, where
>> these numbers come from (in getdiags, this value is only assigned if
>> the diagnostics exceeds "undef", or has not been filled).
>
> See my comments in the code below.
>
>> 2. is it a good idea to reset a diagnostic to "undef", when it is
>> larger than "undef", while "undef" is hardwired? As a counter
>> example: I can image averaging some pressure variable (e.g. bottom
>> pressure anomaly) over many timesteps (or maybe even the square of
>> bottom pressure) and would expect to get really large numbers that
>> are then capped by this logic.
>
> I agree, this is not a good idea. But we need to accomodate with
> fizhi pkg that puts some undef on special occasions.
> If you want to change it, I would recommand something like
>  IF (useFizhi ) THEN / ELSE /ENDIF
>
>>
>> Martin
>>
>>>        IF ( mate.EQ.0 ) THEN
>>> C-      No counter diagnostics => average = Sum / ndiag :
>>>
>>>          ipnt = ip + lev - 1
>>>          factor = FLOAT(ndiag(ip,bi,bj))
>>>          IF (ndiag(ip,bi,bj).NE.0) factor = 1. _d 0 / factor
>>>
>>>          DO j = 1,sNy+1
>>>            DO i = 1,sNx+1
>>>              IF ( qdiag(i,j,ipnt,bi,bj) .LE. undef ) THEN
>>>                qtmp(i,j) = qdiag(i,j,ipnt,bi,bj)*factor
>>>              ELSE
>>>                qtmp(i,j) = undef
>>>              ENDIF
>>>            ENDDO
>>>          ENDDO
>>>
>>>        ELSE
>>> C-      With counter diagnostics => average = Sum / counter:
>>>
>>>          ipnt = ip + lev - 1
>>>          levCt= MIN(lev,kdiag(mate))
>>>          ipCt = im + levCt - 1
>>>          DO j = 1,sNy+1
>>>            DO i = 1,sNx+1
>>>              IF ( qdiag(i,j,ipCt,bi,bj) .NE. 0. ) THEN
>                       ^=== here is where Undef comes from when
>        using a counter diag. Note the 3rd index = ipCt (counter)
>        which is not the same as "ipnt"
>>>                qtmp(i,j) = qdiag(i,j,ipnt,bi,bj)
>>>     &                    / qdiag(i,j,ipCt,bi,bj)
>>>              ELSE
>>>                qtmp(i,j) = undef
>>>              ENDIF
>>>            ENDDO
>>>          ENDDO
>>>
>>>        ENDIF
>>>       ENDIF
>>>
>>
>> _______________________________________________
>> MITgcm-devel mailing list
>> MITgcm-devel at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-devel
> _______________________________________________
> MITgcm-devel mailing list
> MITgcm-devel at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-devel