Opened 3 years ago

Last modified 2 years ago

#572 new task

Vcmax25 no longer used

Reported by: mmcgrath Owned by: somebody
Priority: minor Milestone: Not scheduled yet
Component: Biogeochemical processes Version: trunc
Keywords: Cc:

Description

With the introduction of nitrogen, the parameter Vcmax25 is no longer used to influence photosynthesis. It is still used to calculate vcmax in stomate_vmax, and then passed to diffuco via the assim_param variable. However, the line that would have used it in diffuco has been commented out:

! vcmax(:,:) = assim_param(:,:,ivcmax)

and

! vcmax(:,:) = Vcmax25(jv)

vcmax is now controlled by NUE and NUE_OPT. Vcmax25 has been kept for comparison to old revisions of the code and since that is what many people are still familiar with, printed out in the history files as VCMAX (with VCMAX_NEW printed out as well for the comparison).

There is a concern that people may think VCMAX25 still controls photosynthesis and waste time tuning it. Therefore, perhaps it would be good to remove it completely from the code. The interesting part of vcmax is really leaf_efficiency(:) * leaf_frac(:,j,m), not Vcmax25 (which is a parameter fixed at the beginning of the simulation). Changes could be made to print that out instead.

Change History (2)

comment:1 Changed 3 years ago by mmcgrath

In r6025, I added a little documentation to where Vcmax25 is read in to warn people that it is no longer used.

comment:2 Changed 2 years ago by luyssaert

  • Milestone changed from ORCHIDEE 4.0 to Not scheduled yet
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