[MITgcm-support] Phosphate (PO4) concentration deviates in Offline mode

[Kaushal Gianchandani]

Hello everyone

I am currently using MITgcm to model the biogeochemistry in the context of
paleoclimate. For the same, I have created an offline 2d model that uses
the packages: dic, gchem, ptracers in conjunction with shelfice.

I am facing a problem with the concentration of the nutrient (phosphate -
PO4) in the model --- the concentration does not reach a steady-state.
After just a few years of integration, the concentration deviates
significantly from what it should be. In fact, the initial concentration of
PO4 increases well beyond what I initially start with.

I have gone through many threads provided in [MITgcm-support] dealing with
similar problems but none of the solutions listed there worked for my
problem. I have already tried the following:
1. Used the model with only dissolved organic phosphorus (DOP) and PO4 ---
no problem in this case. The net Phosphorus is conserved and both PO4 and
DOP concentrations reach a steady-state. Somehow the parametrization
for remineralization of particulate organic matter (POP) does not work well
in the offline mode (MITgcm/pkg/dic/phos_flux.F)
2. Running the model without the shelfice package --- the problem persists.
3. Verified that the PTRACERS_EvPrRn is unset.

Please note that the online model with the same configuration works well.
I'd really appreciate any help in this regard.

Thank you,

Regards,
Kaushal.

-- 

*Kaushal Gianchandani*Ph.D. Student in Oceanography
Fredy & Nadine Herrmann Institute of Earth Sciences
Hebrew University of Jerusalem, Israel
Phone: +972-50-471-4621
web: https://kaushalgianchandani.github.io
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20200811/d85815e1/attachment.html>