[MITgcm-support] BLING with variable atmospheric pCO2

[Christoph Voelker]

Hi Matt and Dave,

I understood that Dave did not want atmospheric pCO2 as a prescribed 
function of time/space, but as dynamically evolving through 
uptake/outgassing from the ocean, i.e. a simple atmospheric box that 
accumulates the total air-sea flux (and potentially some terrestrial 
fluxes as prescribed). Is that right?

We have done something like that for our ecosystem model REcoM, based on 
code from the DIC package. It wasn't too hard, but required some 
thinking. For example you want to have an additional restart file, so 
the atmospheric inventory is kept when you do a restart.

Probably you can copy the relevant code by following what happens in the 
DIC package when set DIC_INT=3 in DIC_VARS.h. But if you want I can send 
you the relevant parts of our code, not super-nice to read, but I think 
you can easily grasp the ideas.

Cheers, Christoph


On 21.03.23 14:13, Matthew Mazloff wrote:
> Hi Dave
> 
> It is implemented as long as you are using EXF
> 
> In data.bling you just give the info the exf package needs. For example:
>   apco2file         = 'atm_pco2_capegrim_SO12',
>   apco2period         = 2635200,
>   apco2_interpMethod = 0,
> 
> Then in bling_fields_load it will fill it:
> C Get Atmospheric carbon dioxide concentration from PKG/EXF
> #ifdef ALLOW_EXF
> C     Atmospheric carbon dioxide concentration
>        IF ( useEXF ) THEN
>         IF ( apco2file .NE. ' '  ) THEN
>          CALL EXF_SET_FLD(
>       I     'apco2', apco2file, apco2mask,
> …
> 
> 
> -Matt
> 
> 
>> On Mar 21, 2023, at 5:18 AM, Dave Munday - BAS <danday at bas.ac.uk> wrote:
>>
>> Hi all,
>>
>> I’ve been setting up an idealised model with the intention to use BLING to look at carbon cycling. From looking at the code, I don’t think BLING has an option to have the atmospheric pCO2 dynamically evolve with the ocean carbon storage, like the DIC package does. I could impose a changing pCO2 via input from EXF, but I want to try and conserve the total atmosphere+ocean carbon inventory.
>>
>> Has anyone coded up this option for BLING? Or got some advice on where to start? I’ve been comparing with DIC and it looks like I need to port the calculations in dic_atmos.F across to BLING and then call if from somewhere appropriate. I think this might be in gchem_forcing_sep.F, solely because DIC calls DIC_ATMOS there.
>>
>> Many thanks,
>>
>> Dave
>>
>>
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-- 
Christoph Völker
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
Am Handelshafen 12
27570 Bremerhaven

+49 (0)471-4831-1848
christoph.voelker at awi.de
https://orcid.org/0000-0003-3032-114X