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@samsrabin samsrabin commented Nov 20, 2025

Description of changes

Updated crop maturity requirements and GDD20 baselines using improved scripts and CRU-JRA forcing.

Calibrating crop parameters looking at yield for about 1995-2005 while minimizing failed seasons:

  • Corn: Don't change anything. It's high for 2000-2010 but looks good after that.
  • Cotton: Increase max growing season length from 160 days to 270 days. Causes overwintering, so this will probably need to be reverted! But useful for now to explore how much an extreme change could help with the high failure rate.
  • Rice: Revert CLM5 arooti changes.
  • Soybean: It's low for this period but nothing I tried helped much. Removing mxmat helped a bit, so increase max growing season length from 150 days to 180 days. Accidentally did this for rice instead! Will revert in next crop parameter PR.
  • Sugarcane: Increase max growing season length from 300 days to 360.
  • Wheat: Revert CLM5 arooti changes. Need a pretty big drop in yields and this didn't do it in my test, but that was without grainfill triggering max LAI and thus much more failed crop area. (There were no crop phase parameter changes in CLM5.)

Specific notes

Contributors other than yourself, if any: None

CTSM Issues Fixed:

Are answers expected to change (and if so in what way)? Yes: Any CLM6 crop compset.

Any User Interface Changes (namelist or namelist defaults changes)? New:

  • clm6_0 paramfile
  • Non-GSWP3 stream_fldfilename_cultivar_gdds
  • Non-GSWP3 stream_gdd20_seasons = .false. stream_fldFileName_gdd20_baseline.

Does this create a need to change or add documentation? Did you do so? No

Testing performed, if any:

  • aux_clm in progress
  • Two build-namelist tests fail; I'm assuming these aren't my fault:
1137/3396 < FAIL> <Test Id: 1137> <Desc: useFATESLUH2fileDNE>
1144/3396 < FAIL> <Test Id: 1144> <Desc: inventoryfileDNE>

Derived from half-degree run started 1959-01-01, forced with CRU-JRA, at tag alpha-ctsm5.4.CMIP7.15.ctsm5.3.079. Growing seasons defined by files [sh]dates_ggcmi_crop_calendar_phase3_v1.01_nninterp-hcru_hcru_mt13.2000-2000.20230728_165845.nc. Maximum growing season length in generate_gdds.py derived from mxmat in clm60_params.crop_omni02.c251120.nc with no 'cushion'. generate_gdds.py first season 1995 and last season 2005.
Derived from half-degree run started 1959-01-01, forced with CRU-JRA, at tag alpha-ctsm5.4.CMIP7.15.ctsm5.3.079. generate_gdd20_baseline -v GDDB20 -y1 1995 -yN 2005.
@samsrabin samsrabin added this to the ctsm6.0.0 (code freeze) milestone Nov 20, 2025
@samsrabin samsrabin self-assigned this Nov 20, 2025
@samsrabin samsrabin added the enhancement new capability or improved behavior of existing capability label Nov 20, 2025
@samsrabin samsrabin added science Enhancement to or bug impacting science non-bfb Changes answers (incl. adding tests) labels Nov 20, 2025
@samsrabin samsrabin marked this pull request as ready for review November 20, 2025 23:58
@samsrabin samsrabin changed the title New crop calendar inputs and updated params (omni02) post-5.4.n00: New crop calendar inputs and updated params (omni02) Nov 21, 2025
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@slevis-lmwg slevis-lmwg left a comment

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@samsrabin I looked at your changes. They seem simple enough. Approving.

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I have a couple comments/questions, but this looks good to go. My comments should be addressed in a possible later step. Most of the work was in creating the new datasets that you point to here. So this is deceptively simple compared to the loads of work it took you to get the datasets ready.

<stream_fldFileName_gdd20_baseline cropcals_rx_adapt=".true." stream_gdd20_seasons=".false.">lnd/clm2/cropdata/calendars/processed/gdd20_baseline.c251120.tweaked_latlons.nc</stream_fldFileName_gdd20_baseline>
<stream_fldFileName_gdd20_baseline cropcals_rx_adapt=".true." stream_gdd20_seasons=".false." lnd_tuning_mode="clm4_5_GSWP3v1">lnd/clm2/cropdata/calendars/processed/20230714_cropcals_pr2_1deg.actually2deg.1980-2009.from_GDDB20.interpd_halfdeg.tweaked_latlons.nc</stream_fldFileName_gdd20_baseline>
<stream_fldFileName_gdd20_baseline cropcals_rx_adapt=".true." stream_gdd20_seasons=".false." lnd_tuning_mode="clm5_0_GSWP3v1">lnd/clm2/cropdata/calendars/processed/20230714_cropcals_pr2_1deg.actually2deg.1980-2009.from_GDDB20.interpd_halfdeg.tweaked_latlons.nc</stream_fldFileName_gdd20_baseline>
<stream_fldFileName_gdd20_baseline cropcals_rx_adapt=".true." stream_gdd20_seasons=".false." lnd_tuning_mode="clm6_0_GSWP3v1">lnd/clm2/cropdata/calendars/processed/20230714_cropcals_pr2_1deg.actually2deg.1980-2009.from_GDDB20.interpd_halfdeg.tweaked_latlons.nc</stream_fldFileName_gdd20_baseline>
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This likely means another step, for later, but you'll also want a version for clm6_0 with CRUJRA2024.

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Also it looks like the default for clm4_5 in compsets is GSWP3, but I think we actually used CRUv7 back then. And I think we might change the compsets to reflect that.

However, since this is clm4_5 -- it's also not something to worry about.

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@ekluzek Won't CRUJRA2024 automatically get the new dataset (with c251120 in the filename) because it's not one of the GSWP3v1 tuning modes?

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