[MITgcm-support] Closing DIC budget

[Gregorio Sandy]

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

ATTENTION : Ce courriel provient d'une source externe. Assurez-vous que cette dernière est sûre avant d'ouvrir une pièce jointe ou de cliquer sur un lien. Dans le doute, signalez le message.

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

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20240305/537fce89/attachment-0001.html>