cam6_4_157: namelist changes to support spin-up run by cacraigucar · Pull Request #1509 · ESCOMP/CAM

cacraigucar · 2026-03-18T21:21:06Z

Namelist changes to support Cecile's spin-up run

Closes #1507
Closes #1499

nusbaume

PeterHjortLauritzen

Thanks for putting together this PR. As noted in the specific code comments, I think Danny intentionally set default values for the dust emission factor for CAM7 for various resolutions/dycores that we want to keep. Tagged @dmleung for his input.

PeterHjortLauritzen · 2026-03-19T07:26:38Z

+<dust_emis_fact dyn="se" hgrid="ne30np4"   phys="cam7"             chem="trop_strat_mam5_t1s1">3.2D0</dust_emis_fact>
 <dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam6"    chem="trop_strat_mam5_t1s1">2.0D0</dust_emis_fact>
-<dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam7"    chem="trop_strat_mam5_t1s1">4.0D0</dust_emis_fact>
+<dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam7"    chem="trop_strat_mam5_t1s1">3.2D0</dust_emis_fact>


I don't think we should change the defaults for non 1 degree configurations (this default was set by Danny Leung in late October 2025)

PeterHjortLauritzen · 2026-03-19T07:27:00Z

+<dust_emis_fact dyn="se" hgrid="ne30np4"   phys="cam7"             waccm_phys="1">3.2D0</dust_emis_fact>
 <dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam6"    waccm_phys="1">2.0D0</dust_emis_fact>
-<dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam7"    waccm_phys="1">4.0D0</dust_emis_fact>
+<dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam7"    waccm_phys="1">3.2D0</dust_emis_fact>


I don't think we should change the defaults for non 1 degree configurations (@dmleung?)

PeterHjortLauritzen · 2026-03-19T07:29:15Z


 <dust_emis_fact hgrid="1.9x2.5"                   phys="cam6"    ver="chem">0.65D0</dust_emis_fact>
-<dust_emis_fact hgrid="1.9x2.5"                   phys="cam7"    ver="chem">4.0D0</dust_emis_fact>
+<dust_emis_fact hgrid="1.9x2.5"                   phys="cam7"    ver="chem">3.2D0</dust_emis_fact>


I don't think we should change the defaults for non 1 degree configurations (@dmleung?)

PeterHjortLauritzen · 2026-03-19T07:29:29Z

+<dust_emis_fact hgrid="1.9x2.5"   offline_dyn="1" phys="cam7"    ver="chem">3.2D0</dust_emis_fact>
 <dust_emis_fact hgrid="0.47x0.63" offline_dyn="1" phys="cam6"    ver="chem">2.25D0</dust_emis_fact>
-<dust_emis_fact hgrid="0.47x0.63" offline_dyn="1" phys="cam7"    ver="chem">4.0D0</dust_emis_fact>
+<dust_emis_fact hgrid="0.47x0.63" offline_dyn="1" phys="cam7"    ver="chem">3.2D0</dust_emis_fact>


I don't think we should change the defaults for non 1 degree configurations

PeterHjortLauritzen · 2026-03-19T07:30:50Z

+<dust_emis_fact hgrid="1.9x2.5"                   phys="cam7"    ver="chem">3.2D0</dust_emis_fact>
 <dust_emis_fact hgrid="0.9x1.25"                  phys="cam6"    ver="chem">1.75D0</dust_emis_fact>
-<dust_emis_fact hgrid="0.9x1.25"                  phys="cam7"    ver="chem">4.0D0</dust_emis_fact>
+<dust_emis_fact hgrid="0.9x1.25"                  phys="cam7"    ver="chem">3.2D0</dust_emis_fact>


@dmleung we are changing dust_emis_fact for the workhorse model (1 degree SE). Should we change the 1 degree FV value too?

PeterHjortLauritzen · 2026-03-19T07:31:59Z

+<dust_emis_fact hgrid="0.9x1.25"                  phys="cam7"    ver="chem">3.2D0</dust_emis_fact>
 <dust_emis_fact hgrid="1.9x2.5"   offline_dyn="1" phys="cam6"    ver="chem">0.6D0</dust_emis_fact>
-<dust_emis_fact hgrid="1.9x2.5"   offline_dyn="1" phys="cam7"    ver="chem">4.0D0</dust_emis_fact>
+<dust_emis_fact hgrid="1.9x2.5"   offline_dyn="1" phys="cam7"    ver="chem">3.2D0</dust_emis_fact>


I don't think we should change the defaults for non 1 degree configurations (@dmleung)

PeterHjortLauritzen · 2026-03-19T07:32:40Z

 <dust_emis_fact dyn="se" hgrid="ne30np4"   phys="cam6"             chem="trop_strat_mam4_vbs">2.0D0</dust_emis_fact>
-<dust_emis_fact dyn="se" hgrid="ne30np4"   phys="cam7"             chem="trop_strat_mam4_vbs">4.0D0</dust_emis_fact>
+<dust_emis_fact dyn="se" hgrid="ne30np4"   phys="cam7"             chem="trop_strat_mam4_vbs">3.2D0</dust_emis_fact>
 <dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam6"    chem="trop_strat_mam4_vbs">2.0D0</dust_emis_fact>


I don't think we should change the defaults for non 1 degree configurations (@dmleung)

PeterHjortLauritzen · 2026-03-19T07:32:49Z

+<dust_emis_fact dyn="se" hgrid="ne30np4"   phys="cam7"             chem="trop_strat_mam4_vbs">3.2D0</dust_emis_fact>
 <dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam6"    chem="trop_strat_mam4_vbs">2.0D0</dust_emis_fact>
-<dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam7"    chem="trop_strat_mam4_vbs">4.0D0</dust_emis_fact>
+<dust_emis_fact dyn="se" hgrid="ne0np4CONUS.ne30x8" phys="cam7"    chem="trop_strat_mam4_vbs">3.2D0</dust_emis_fact>


I don't think we should change the defaults for non 1 degree configurations (@dmleung)

dmleung · 2026-03-19T17:56:51Z

Hi @PeterHjortLauritzen and @cacraigucar , thanks for putting this together and for pinging me! I have an issue to bring up here.

-I think I put dust_emis_fact = 4.0 for phys="cam7" for the ne30 case in #1426. 4.0 works good for the F cases in 1°.
-For B cases, @adamrher and I agreed to use dust_emis_fact = 3.2, mainly because dust in the CTSM–BGC mode in the B case was quite a bit smaller, given larger LAI in the arid/semiarid areas in the BGC mode (per my discussion with Will and Dave).
-I set dust_emis_fact = 4.0 mainly for the 1° F case. But @cacraigucar I wonder if there is a way to separate dust_emis_fact values for the F cases and B cases? Or, is there a way to separate dust_emis_fact values for the CTSM–SP an CTSM–BGC?

Thanks for putting together this PR. As noted in the specific code comments, I think Danny intentionally set default values for the dust emission factor for CAM7 for various resolutions/dycores that we want to keep. Tagged @dmleung for his input.

Regarding the default values for various resolutions/dycores, I actually didn't have time to test different resolutions; I just tested and changed the value for the nominal ne30 res for cam7 physics based on the tested dust_emis_fact value, from 2.3 to 4.0 (see #1426). I changed all other values in other res by scaling the old values up by a factor of 4.0/2.3 ~ 1.7 in #1426. I hope this makes sense.
I previously tested runs using dyn="se" vs dyn="fv", and this change seems to make a small difference. So, they can share the same dust_emis_fact given the same res.

So, the current main issue I think is to separate dust_emis_fact values between F and B cases, so you can prescribe 4.0 for F cases and 3.2 for B cases. I wonder if this is possible. thanks

cacraigucar · 2026-03-19T19:48:17Z

@PeterHjortLauritzen @dmleung - Could you please verify that the dust setting for the run that Cecile will be making has the correct dust value for the spin-up run? I then propose that we open an issue to adjust the dust settings for the other configurations and address that at a later time. The scope of this PR is simply to get Cecile's settings into CAM and there is a time crunch to get this through.

dmleung · 2026-03-19T19:56:46Z

@PeterHjortLauritzen @cacraigucar it looks like from #1507 that dust_emis_fact = 3.2 is used for the spinup run in the B case. I don't exactly see the case dir, but 3.2 is good for a B case for CAM7 physics.
@cacraigucar it would be great if you could come up with a way to separate dust_emis_fact for F and B cases in another issue at a later time!

cacraigucar · 2026-03-19T20:01:25Z

My specific question (and this is probably for @PeterHjortLauritzen) is that there are a number of dust settings for cam7 which I changed back at his request. I want to make sure that the configuration that Cecile will be running has the correct setting in the code mods that I will be committing.

adamrher · 2026-03-19T20:42:19Z

This is the entry that will be used in Cecile's spinup:

https://github.com/cacraigucar/CAM/blob/ddca361cf06c15c1c62da7734ed7699e48dfd3f1/bld/namelist_files/namelist_defaults_cam.xml#L2552

And it's correct.

I then propose that we open an issue to adjust the dust settings for the other configurations and address that at a later time. The scope of this PR is simply to get Cecile's settings into CAM and there is a time crunch to get this through.

In the interest of time, I'd agree. My feeling (perhaps woefully uninformed) is that it's not straight forward to key off a namelist value based on the components of the compset. I think the determining factor should be the CLM specifiers %BGC or %SP, but I'm not sure how possible that is unless we make CLM the owner of this namelist. Which is a back and forth we've been having for a while now.

cacraigucar · 2026-03-19T20:49:19Z

This is the entry that will be used in Cecile's spinup:

https://github.com/cacraigucar/CAM/blob/ddca361cf06c15c1c62da7734ed7699e48dfd3f1/bld/namelist_files/namelist_defaults_cam.xml#L2552

And it's correct.

I then propose that we open an issue to adjust the dust settings for the other configurations and address that at a later time. The scope of this PR is simply to get Cecile's settings into CAM and there is a time crunch to get this through.

In the interest of time, I'd agree. My feeling (perhaps woefully uninformed) is that it's not straight forward to key off a namelist value based on the components of the compset. I think the determining factor should be the CLM specifiers %BGC or %SP, but I'm not sure how possible that is unless we make CLM the owner of this namelist. Which is a back and forth we've been having for a while now.

@adamrher - Thank you for the confirmation. Peter had me simplify the namelist to remove the chemistry qualifiers for this PR. You just confirmed that what we did made sense! We will need to open a new issue to address the rest of the dust settings in a future PR

cacraigucar · 2026-03-19T20:49:57Z

@dmleung Could you please open an issue with your request for dust setting enhancements?

dmleung · 2026-03-19T22:06:35Z

@cacraigucar @adamrher
Thanks! Yes, I can write up an issue on this.

namelist changes to support spin-up run

a2eb29b

cacraigucar requested review from JulioTBacmeister, PeterHjortLauritzen and cecilehannay March 18, 2026 21:21

cacraigucar self-assigned this Mar 18, 2026

cacraigucar added this to CAM Development Mar 18, 2026

nusbaume self-requested a review March 18, 2026 21:28

nusbaume approved these changes Mar 18, 2026

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Comment thread bld/namelist_files/namelist_defaults_cam.xml Outdated

cacraigucar added 2 commits March 18, 2026 15:56

Fix one additional namelist variable

f27b8b1

Add updated ndep file

79e9a1c

PeterHjortLauritzen reviewed Mar 19, 2026

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cacraigucar added 2 commits March 19, 2026 07:57

Address review comments

5e07804

More review changes

6f75857

cacraigucar requested a review from PeterHjortLauritzen March 19, 2026 14:44

Mods for dust for the spin-up run

ddca361

PeterHjortLauritzen approved these changes Mar 19, 2026

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cacraigucar closed this Mar 19, 2026

github-project-automation bot moved this to Done in CAM Development Mar 19, 2026

cacraigucar reopened this Mar 19, 2026

ChangeLog for cam6_4_157

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cacraigucar merged commit b5e0050 into ESCOMP:cam_development Mar 21, 2026
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github-project-automation bot moved this from Done to Tag in CAM Development Mar 21, 2026

cacraigucar deleted the cam_cecile_namelist branch March 21, 2026 01:53

dmleung mentioned this pull request Mar 24, 2026

dust_emis_fact needs separate values for F and B cases #1516

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