Possible unit error in cmorized variable fNup

[oyvindseland]

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Anyone who recognize this variable

Øyvind

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I've been looking at fNup in the CMIP6 simulations available on ESGF, and there's something a bit odd about the NorESM2 values. They're roughly 5 orders of magnitude bigger than I'd expect, given the values for the other models (particularly CESM2).

An accident with formatting with days rather than seconds would probably account for this. *86400 gives a more sensible value. (No judgement here, formatting ncdf files is a pain.) Please can you check your data and let me know if this is the case?

The file/s are: fNup_Emon_NorESM2-LM_historical_r1i1p1f1_gn_195001-195912 to the end of the historical simulation. I've briefly looked at fNup_Emon_NorESM2-LM_ssp370_r1i1p1f1_gn_201502-202012 and this seems to be out by about the same amount.

Cheers,
T

--

T Davies-Barnard (she/her, please call me T)

College of Engineering, Mathematics and Physical Sciences
University of Exeter

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[lca041]

I have checked the CMOR table for the variable fNup, and it looks like the unit is in second. I could not find a reasonable answer to this abnormally bg value in NorESM2.

[kjetilaas]

Hi @oyvindseland and @YanchunHe . I have now looked into this with @huitang-earth, and it seems like the wrong variable has been used for the cmorization. "fNup_Emon_NorESM2..." seems to have used "SMINN_TO_PLANT" as the original variable. However, this variable is not used with the new FUN nitrogen uptake model. Instead, "NUPTAKE" should be used (like in CESM cmorized data).

[YanchunHe]

Thanks to looking into this, @kjetilaas !

Indeed SMINN_TO_PLANT is used as original input for fNup. This has been implemented for long as specified in the "CMIP6 data request Google Sheet file" (can share the link if you request). I can't recall when this is initially used.

If this is the case, all fNup in the cmorized and publish files are wrong.

Then we may need to report and errata in the ESGF Doc page, for all the published fNup, @monsieuralok ?

I don't think it is practical to retract all, redo the cmorization and republish fNup for all the experiments, but possibly we can recmorize some experiments if user really requests.

[monsieuralok]

@YanchunHe from which experiments should be retract fNup values?

[YanchunHe]

@YanchunHe from which experiments should be retract fNup values?

We should retract it from all the experiments, as all of them are wrong.
I will have to recmorize at least the CMIP and ScenarioMIP experiments, and they should be republished.
Not clear for me how it is important for other experiments.

[monsieuralok]

@YanchunHe Should fNup be removed even recently published pi-Control experiment? That, I have published yesterday. Also for, NorESM2-LM, NorESM2-MM and NorESM1-F ?

[YanchunHe]

Yes, please remove all of the existing fNup from ESGF, including the piControl exp.

[ryanarta]

Hi @YanchunHe and @kjetilaas: I have now modified the Google Sheet file with the right variable. @oyvindseland was right, the two variables ("SMINN_TO_PLANT" and "NUPTAKE") differ roughly by five orders of magnitude.

[YanchunHe]

These new variables have been cmorized for (most of) the CMIP, AerChemMIP and ScenarioMIP experiments by NorESM2-LM and NorESM2-MM (as refereed by above list). They are in the queue to be published to ESGF.

Close this issue now.
(reopen whenever find needed)