[MITgcm-devel] gchem

[Stephanie Dutkiewicz]

On Tue, 26 Oct 2004, Martin Losch wrote:

> Hi,
> 
> here comes my share of (hopefully not stupid) suggestions for this week.
> 
> I have several questions and suggestions about the GCHEM package:
> 1. There is one experiment dic_example, but testreport probably does 
> not check the values of the passive tracers. Is there a way to check, 
> whether I broke this experiment by my modifications other than 
> acutually comparing the output fields?

I believe there was talk of using the monitor output
%MON
to check that such experiments were still working.
Has anyone done that yet?

> 
> 2. the place of the call gchem_forcing_sep in forward_step doesn't make 
> sense to me. Why isn't it called before do_fields_blocking_exchanges? I 
> would like to change that, and then iMin,iMax,jMin,jMax could be set to 
> 1,sNx,1,sNy (instead of 1-Olx,sNx+Olx, etc) in gchem_forcing_sep and we 
> wouldn't have to compute the expensive bio-forcing on the halos at all 
> (I think, this causes problem with my open boundary set-up), the fields 
> are exchanged anyway. This change doesn't require any work and I am 
> willing to do that, but I don't know if it will break dic_example 
> (probably not).
> [The more complicated solution is to call gchem_forcing_sep much 
> earlier, eg. after call seaice, but I am not even suggesting that, 
> because it will require changing the way the time step is handled in 
> all bgc_forcing.F files.]

I have no problems if you want to make this change. Just make sure
that all diagnostics etc are still working correctly.
I had not done so because I thought it cleaner to pass the ptracers
rather than remembering to use the gPtr ...

> 
> 3. gchem_fields_load calls subroutines 
> (dic_fields_load/cfc_fields_load, and whatever I added in my local 
> copy), but in these subroutines, files are read whose names are defined 
> in GCHEM.h (WindFile, AtmospFile, etc.). Wouldn't it make more sense to 
> read those files in gchem_fields_load directly? Parts of 
> cfc_fields_load and dic_fields_load are identical (and for every 
> bgc-model I have, I have to duplicate these files again. Also I makes 
> it hard to interface gchem_fields_load with the exf-package (I am 
> probably the only one who wants to do that).

The problem with doing is this way, is that not all package use all
the files. For instance feinput files are only used in the
DIC package - and so InputFe 
(which is bWght*feinput0(i,j,bi,bj)
     &                          +aWght*feinput1(i,j,bi,bj) )

is defined in DIC_LOAD.h -- a file which the gchem pkg doesn't
see.

> 
> Martin
> 


steph