[MITgcm-support] Passive tracer decoupling from convection

[Yuxin Zhou]

Hi Spencer,
Thanks for the reply. I tested out two of your ideas. After hosing for one
year, I first let the AMOC recover for 100 years. Oxygen basically remained
the same. Then I hosed with 5Sv of freshwater for ten years. AMOC is
basically gone at this point:
[image: image.png]

However, oxygen still didn't change much:
[image: image.png]

Going forward, I might test out the different advection schemes and other
ptracer parameters to see if that helps. Again, I appreciate your help.

Best,
Yuxin

On Wed, Sep 1, 2021 at 10:29 PM Spencer Jones <spencerjones at tamu.edu> wrote:

> Dear Yuxin,
> It seems to me that maybe you just didn't run for long enough to see any
> change in the oxygen concentration. From your email it seems like you only
> ran for 1 year. Is that right? I wouldn't expect the oxygen concentration
> to change until several years (maybe even decades) after hosing has taken
> place, and only to change if the reduction in the AMOC continues (i.e. you
> might want to continue hosing, rather than switching it off).
>
> I'm not sure why tutorial_global_oce_biogeo doesn't match with
> observations, but usually the tutorial experiments are set up to
> demonstrate the model functionality, not to provide a very realistic
> simulation. You might need to put more work into improving the forcing
> fields and/or resolution in order to get realistic output.
> Good luck ,
> Spencer
>
> On Tue, Aug 31, 2021 at 9:28 PM Yuxin Zhou <yzhou at ldeo.columbia.edu>
> wrote:
>
>> Hi all,
>> I'm running the tutorial_global_oce_biogeo experiment and analyzing the
>> oxygen results and I found some weird behaviors. Any help would be
>> appreciated.
>>
>> Here is the AMOC stream function in equilibrium, which looks normal:
>> [image: image.png]
>>
>> Here is the AMOC stream function after a hosing of 5 Sv for one year
>> (by increasing precipitation in the 50-70N North Atlantic region), which
>> looks normal too. It shows a weakened NADW:
>> [image: image.png]
>>
>> Here is the oxygen concentration of the AMOC cross-section in equilibrium:
>> [image: image.png]
>>
>> Here is the oxygen concentration after the hosing:
>> [image: image.png]
>>
>> Firstly, the oxygen concentration of the AMOC in equilibrium does not
>> reflect modern observations such as the World Ocean Atlas, which shows
>> oxygenated water closely following the presence of the NADW. Secondly,
>> oxygen basically doesn't change even though circulation changed
>> dramatically. It seems convection processes barely impact oxygen at all.
>>
>> Has anyone else seen this behavior? Any suggestions for tests I can run
>> to figure out what's wrong?
>>
>> Thanks,
>> Yuxin
>> --
>> Yuxin Zhou
>> https://www.ldeo.columbia.edu/~yzhou/
>> <https://urldefense.com/v3/__https://www.ldeo.columbia.edu/*yzhou/__;fg!!KwNVnqRv!XGV-_ZoSHtQ8Iafno1yNILLkNCN6MaDMwIwpWla_Ftn5cl116QSs05k-WzMaoC6wDGs$>
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>>
>> https://urldefense.com/v3/__http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support__;!!KwNVnqRv!XGV-_ZoSHtQ8Iafno1yNILLkNCN6MaDMwIwpWla_Ftn5cl116QSs05k-WzMa3wNpf4E$
>>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support
>


-- 
Yuxin Zhou
https://www.ldeo.columbia.edu/~yzhou/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210902/e3b22f19/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 52824 bytes
Desc: not available
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210902/e3b22f19/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 54004 bytes
Desc: not available
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210902/e3b22f19/attachment-0007.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 59168 bytes
Desc: not available
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210902/e3b22f19/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 59071 bytes
Desc: not available
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210902/e3b22f19/attachment-0009.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 45030 bytes
Desc: not available
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210902/e3b22f19/attachment-0010.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 58707 bytes
Desc: not available
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210902/e3b22f19/attachment-0011.png>