Bring the carbon isotope fix to the release branch #698
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ekluzek
added
type: bug - impacts science
priority: high
AGonzalezNicolas
pushed a commit
to HPSCTerrSys/clm5_0
that referenced
this pull request
Jun 27, 2024
Bring the carbon isotope fix to the release branch
AGonzalezNicolas
pushed a commit
to HPSCTerrSys/clm5_0
that referenced
this pull request
Jul 5, 2024
Bring the carbon isotope fix to the release branch
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Description of changes
Fix the Carbon isotope bug for transient land-use change on the release branch (brings in changes from ctsm1.0.dev036 to release branch).
Specific notes
We currently have a bug so that for transient land-use change cases answers are different starting in soil
carbon when Carbon isotopes (use_c13, or use_c14) are on versus off. Answers are identical if there is no
land-use change. The bug does cause bulk Carbon (C12) to be slightly different, but qualitatively the same.
There is a significant impact to the Carbon isotope simulation however. The bug was causing changes in isotopic
pools to be directed to the bulk Carbon. Because, isotopes are so much smaller than bulk Carbon, this doesn't
cause a marked difference in the bulk Carbon simulation. But, the lack of the change in the isotopic pool
does have a meaningful impact on the simulation of the Carbon isotopic fields.
Also added a general test for this and specific one to catch this case.
Contributors other than yourself, if any: @klindsey, @olyson @dlawren @billsacks @bishtgautam
CTSM Issues Fixed (include github issue #):
Fixes #675
Fixes #686
Are answers expected to change (and if so in what way)? Yes
Answers change quantitatively (but not qualitatively) for bulk Carbon when use_c13 or use_c14 is on, but C13 and C14 is wrong over areas with land-use change after the years boundary happens. The effect is especially strong with soil Carbon.
Any User Interface Changes (namelist or namelist defaults changes)? No
Testing performed, if any: standard testing on cheyenne
http://webext.cgd.ucar.edu/I20TR/clm50_release-clm5.0.20_1deg_GSWP3V1_isofix2_hist/lnd/clm50_release-clm5.0.20_1deg_GSWP3V1_isofix2_hist.1995_2014-clm50_release-clm5.0.20_1deg_GSWP3V1_isofix_hist.1995_2014/setsIndex.html