[MITgcm-support] coupling issues

[David Ferreira]

Hi Alexandre,

About the dic problem, you should be able to see in the STDOUT which 
package the model was reading when it stopped (ocean and atmosphere). 
Likeky it is data.aimphys in the atmsophere:

So a blind try: did you add a namelist in data.aimphys for the CO2. An 
example:

  &AIM_PAR_CO2
   Aim_CO2_Flag=2,
   atmpCO2init= 325.6E-6,
  &

The first flag is for interactive (2)/precribed (1) CO2. The second one 
is the initial atmospheric pCO2.

Another thing that comes to mind (but is likely not related to your 
namelist problem).
In shared_code/ATMIDS.h, you need to activate the transfer of the CO2 
variables.

C     Pass carbon/DIC variables only if flag set below
       LOGICAL atmCpl_exchange_DIC
       PARAMETER( atmCpl_exchange_DIC = .TRUE.)

About the insolation problem, the first option is that SOLC is modified 
in data.aimphys at running time. Otherwise, did you turn 
ALLOW_INSOLATION on in AIM_OPTIONS.h?
If no, the model uses an approximated formula and it could be biased 
(which would be good to know). If yes, then the model used a more 
sophisticated formulae which I coded (from Berger 78 and could be 
wrongly coded).  Which would be good to know too.

cheers,
david


On 4/10/15 10:09 AM, Alexandre Pohl wrote:
> Dear all,
>
> I am trying to set a coupled ocean-atmosphere configuration of the MITgcm, and I am now getting stuck due to several coupling issues.
>
> The first one concerns the pkg/seaice. I wanted to use it in conjunction with the pkg/thsice at first, but I am now wondering if using the pkg/seaice is simply possible in a coupled setup or not. Which strikes me, is the fact that using the pkg/seaice requires activating the pkg/exf, which seems to have been constructed to force the OGCM. I saw a few flags in EXF_OPTIONS.h, that have to be defined when pkg/aim_v23 is used, or when the pkg/seaice is activated. But what should I do if both are used? Is there any way to use the pkg/seaice without using any external surface forcing file, i.e. using only variables computed by aim_v23?
>
> Another coupling issue concerns the pkg/dic. I would like to allow CO2 exchanges between the ocean and the atmosphere, and I consequently thought the flag 'ALLOW_AIM_CO2' had to be defined within AIM_OPTIONS.h. While compiling the code goes well with this flag turned on, execution shortly ends without any explicit error message. I get a compiler 'namelist' error, with no additional information. Has anyone else experienced this before? Is there a workaround? Note that with the flag turned off, the code works well.
>
> Finally, I noticed something strange in my outputs. Although SOLC is set to 342 W/m2 in 'phy_const.h', the output diagnostic FSOL gives an annual globally-averaged value of 344.5 W/m2 (value directly computed on the non-interpolated CS grid). After a quick look at the code, it seems right to me that FSOL varies in time due to orbital variations, but I cannot figure out why the annual mean value differs from SOLC...
>
> Any help would be welcome, should it concern one or the other of these issues.
> Thanks in advance,
>
> Alexandre Pohl
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