Alternative cost functions in FUN

[wwieder]

New work by Tom Bytnerowicz @tbytnero generated a revised temperature function for nitrogen fixation that could replace the Houlton et al function we're currently using in FUN.

CTSM/src/biogeochem/CNFUNMod.F90

Line 1606 in bc7c8a3

fun_cost_fix = (-1*s_fix) * 1.0_r8 / (1.25_r8* (exp(a_fix + b_fix * tc_soisno * (1._r8 - 0.5_r8 * tc_soisno / c_fix)) ))

This also could be applied in FATES, @ckoven & @rgknox ?

I'm opening this issue as a place holder to record ideas about when and how to best try out the new temperature function in the model.

Definition of DONE:

• Tom's NFIX by default for clm6_0
• New paramfile with higher survivability and less absurd parameter choices (see 1-deg I-case spin-up and historical to test new paramfile for CESM3 (ctsm53019_f09_BNF_[AD, SASU, pSASU, hist]) NCAR/LMWG_dev#89)
• New IC files for FV09 1850 (see 1-deg I-case spin-up and historical to test new paramfile for CESM3 (ctsm53019_f09_BNF_[AD, SASU, pSASU, hist]) NCAR/LMWG_dev#89), new ne30 1850 may be best but not available at this time
• ./rimport new files as needed (slevis clarification: To resolve izumi aux_clm failures)
• Remove testmods_dirs/clm/flexCN_FUN_BNF and corresponding test(s) as redundant #2983

[slevis-lmwg]

Since we didn't close this issue when #2869 got merged to main (via b4b-dev), I will link this issue to my upcoming PR where "Bytnerowicz" becomes the default.

[slevis-lmwg]

Definition of DONE:

• Tom's NFIX by default for clm6_0
• New paramfile with higher survivability and less absurd parameter choices (see 1-deg I-case spin-up and historical to test new paramfile for CESM3 (ctsm53019_f09_BNF_[AD, SASU, pSASU, hist]) NCAR/LMWG_dev#89)
• New IC files for FV09 1850 (see 1-deg I-case spin-up and historical to test new paramfile for CESM3 (ctsm53019_f09_BNF_[AD, SASU, pSASU, hist]) NCAR/LMWG_dev#89), new ne30 1850 may be best but not available at this time
• ./rimport new files as needed
• Open issue to remove this testmod and corresponding test(s) as redundant: cime_config/testdefs/testmods_dirs/clm/flexCN_FUN_BNF