[MITgcm-support] Closing DIC budget

[Martin Losch]

Hi,

you can also try to set exactConserv = .TRUE., in data (but I am not sure if there’s an effect on the passive tracers).

I am not sure, but I think that the tracer conservation will improve very much with the nonlinear free surface. verification/tutorial_global_oce_biogeo does not use a nonlinear free surface. To turn it on, you’d need to define NONLIN_FRSURF (in  CPP_OPTIONS.h), recompile (“make”) and use the appropriate runtime flags:  nonlinFreeSurf=4, select_rStar=2, and maybe hFacInf, hFacSup.

Martin

> On 6. Mar 2024, at 17:41, Wenrui Jiang <wjiang33 at jhu.edu> wrote:
> 
> Hi Sandy,
> 
> Thank you very much for the suggestion. Although I have not figured out everything yet, but it is now much closer to a closure. Thank you!
> 
> Best,
> Wenrui
> 
> From: MITgcm-support <mitgcm-support-bounces at mitgcm.org <mailto:mitgcm-support-bounces at mitgcm.org>> on behalf of Gregorio Sandy <Sandy.Gregorio at uqar.ca <mailto:Sandy.Gregorio at uqar.ca>>
> Sent: Tuesday, March 5, 2024 11:13 AM
> To: mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org> <mitgcm-support at mitgcm.org <mailto:mitgcm-support at mitgcm.org>>
> Subject: Re: [MITgcm-support] Closing DIC budget
>  
> 
>       External Email - Use Caution      
> 
> 
> Hi Wenrui,
> 
> I had a problem as well in closing my tracers budget (by just looking at timeseries of my tracers integrated over my domain, I could see a drift). I don't know if it can help you but I added the following line in data.ptracers for all my tracers (1 to 5):
> 
> PTRACERS_linFSConserve(1)=.TRUE.,
> PTRACERS_linFSConserve applies mean Free-Surf source/sink at surface.
> Good luck,
> 
> Sandy
> De : MITgcm-support <mitgcm-support-bounces at mitgcm.org> de la part de Wenrui Jiang <wjiang33 at jhu.edu>
> Envoyé : lundi 4 mars 2024 13:18
> À : mitgcm-support at mitgcm.org <mitgcm-support at mitgcm.org>
> Objet : [MITgcm-support] Closing DIC budget
>  
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> 
> Dear MITgcm support group,
> 
> Thanks for reading this. My name is Wenrui Jiang, and I am a PhD student from Johns Hopkins. I want to apologize in advance for my inexperience.
> 
> I am trying to close the DIC budget on the biogeochemical tutorial example (https://mitgcm.readthedocs.io/en/latest/examples/global_oce_biogeo/global_oce_biogeo.html). The diagnostics that I include are:
> 
> TRAC01  |SMR     MR|mol/m^3         |Dissolved Inorganic Carbon (DIC) [mol C/m^3] concentration
> ForcTr01|SMR     MR|mol/m^3/s       |DIC forcing tendency
> AB_gTr01|SMR     MR|mol/m^3/s       |DIC tendency from Adams-Bashforth
> Tp_gTr01|SMR     MR|mol/m^3/s       |DIC total transport tendency (before gchem_forcing_sep)
> ADVrTr01|WM      LR|mol/m^3.m^3/s   |Vertical   Advective Flux of DIC
> ADVxTr01|UU      MR|mol/m^3.m^3/s   |Zonal      Advective Flux of DIC
> ADVyTr01|VV      MR|mol/m^3.m^3/s   |Meridional Advective Flux of DIC
> DFrETr01|WM      LR|mol/m^3.m^3/s   |Vertical Diffusive Flux of DIC (Explicit part)
> DFxETr01|UU      MR|mol/m^3.m^3/s   |Zonal      Diffusive Flux of DIC
> DFyETr01|VV      MR|mol/m^3.m^3/s   |Meridional Diffusive Flux of DIC
> DFrITr01|WM      LR|mol/m^3.m^3/s   |Vertical Diffusive Flux of DIC (Implicit part)
> 
> DICBIOA | 15 |SM P    MR      |mol/m3/sec      |Biological Productivity (mol/m3/s)
> DICCARB | 15 |SM P    MR      |mol eq/m3/sec   |Carbonate chg-biol prod and remin (mol eq/m3/s)
> DICTFLX |  1 |SM P    L1      |mol/m3/sec      |Tendency of DIC due to air-sea exch (mol/m3/s
> 
> So far, I managed to close the Tp_gTr01 term with the advective and diffusive flux in the interior to machine precision. However, at the surface there is a large residual, which I am not able to close with ForcTR01. I am wondering if this is a dilution effect from PTRACER_ref.
> 
> I am also having a hard time matching Tp_gTr01 and the tendency diagnosed from DIC and Eta snapshots using the GCHEM diagnostics. The GCHEM diagnostics seems to have very small value (10^-10 mol/m^3/s) which is much smalller than the difference.
> 
> I would really appreciate it if you could tell me whether:
> 
>   1. I am using the correct diagnostics in the correct way;
>   2.there are any model setups that prevent a tracer closure.
> 
> Thank you very much!
> 
> Sincerely,
> Wenrui
> 
> Wenrui Jiang
> 
> Ph.D. Student,
> Department of Earth & Planetary Sciences,
> Johns Hopkins University.
> 
> Email: wjiang33 at jh.edu
> 
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