Set -megan flag for coupled compsets using _simple SOA_ scheme in CAM-Chem

[wwieder]

Brief summary of bug

Out of the box (CESM beta04 tag) does not set -megan flag in CLM_BLDNML_OPTS.
It seems like this should be on by default for B (and F-) cases using the simple SOA scheme in cam-chem.

General bug information

Recent CESM simulations by @cecilehannay are not passing megan fields to the atmosphere. See BLTHIST_121

@lkemmons noted that the 'Simple SOA' scheme, published by Duseong Jo, now depends on MEGAN biogenic emissions so that SOA varies with climate change (unlike in CESM2, CMIP6). So, the -megan flag ought to be on.

Are there other user_nl_clm or user_nl_cam changes that should also come along with turning this flag on?

CTSM version you are using: [output of git describe]
cesm_beta04 and earlier cesm_dev runs (e.g. 104)

Does this bug cause significantly incorrect results in the model's science? [Yes / No]
Yes

Configurations affected: [Fill this in if known.]
B (and F?) cases using the 'Simple SOA' scheme.

Note this likely also is related to #2710, but focuses more on the out-of-the-box features

[ekluzek]

@wwieder the primary purpose of the "--megan" flag in CTSM is to provide a way to run with MEGAN for standalone CLM and also for us to test that way. Because, different CAM-Chem options are really particular about the set of MEGAN species are needed for each option -- we normally let CAM-Chem be the expert on the list of species that are needed for the particular scenario.

So I suspect the same should be done here the specifications for MEGAN for the simple SOA scheme should probably be in CAM-Chem with the other scenarios. II'll look over Cecile's case and see what I can figure out about this setup,

Technically a user can set their own specifications for MEGAN by either turning it on in CTSM OR doing something similar in CAM. It just changes whether you modify the user_nl_clm file or the user_nl_cam file.

[dlawrenncar]

Note that Simone seems to think that MEGAN is on (see below) and I think this implies that fluxes are being passed to CAM. It would be good to confirm this and understand how this gets set up. From Simone: MEGAN is on, you have to look at drv_flds_in not atm_in for that, see below. If we get a higher burden, we also have higher deposition rates, so I assume it makes sense. I agree with Rebecca, we could save out the Megan emissions for a year and see how different they are. If Justin can run the aerosol budgets, that would be good; then we can see how much the numbers differ. Or else I can run them when I am back, Cheers, Simone &megan_emis_nl megan_factors_file = '/glade/campaign/cesm/cesmdata/inputdata/atm/cam/chem/trop_mozart/emis/ megan21_emis_factors_78pft_c20161108.nc' megan_mapped_emisfctrs = .false. megan_specifier = 'SOAE = 0.5954*isoprene + 5.1004*(carene_3 + pinene_a + thujene_a + bornene +', ' terpineol_4 + terpineol_a + terpinyl_ACT_a + myrtenal + sabinene + pinene_b + camphene +', ' fenchene_a + limonene + phellandrene_a + terpinene_a + terpinene_g + terpinolene +', ' phellandrene_b + linalool + ionone_b + geranyl_acetone + neryl_acetone + jasmone +', ' verbenene + ipsenol + myrcene + ocimene_t_b + ocimene_al + ocimene_c_b + 2met_nonatriene) + ', ' 12.3942*(farnescene_a + caryophyllene_b + acoradiene + aromadendrene + bergamotene_a +', ' bergamotene_b + bisabolene_a + bisabolene_b + bourbonene_b + cadinene_d + cadinene_g +', ' cedrene_a + copaene_a + cubebene_a + cubebene_b + elemene_b + farnescene_b +', ' germacrene_B + germacrene_D + gurjunene_b + humulene_a + humulene_g + isolongifolene +', ' longifolene + longipinene + muurolene_a + muurolene_g + selinene_b + selinene_d +', ' nerolidol_c + nerolidol_t)' /

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On Thu, Jan 23, 2025 at 1:57 AM Erik Kluzek ***@***.***> wrote: @wwieder <https://github.com/wwieder> the primary purpose of the "--megan" flag in CTSM is to provide a way to run with MEGAN for standalone CLM and also for us to test that way. Because, different CAM-Chem options are really particular about the set of MEGAN species are needed for each option -- we normally let CAM-Chem be the expert on the list of species that are needed for the particular scenario. So I suspect the same should be done here the specifications for MEGAN for the simple SOA scheme should probably be in CAM-Chem with the other scenarios. II'll look over Cecile's case and see what I can figure out about this setup, Technically a user can set their own specifications for MEGAN by either turning it on in CTSM OR doing something similar in CAM. It just changes whether you modify the user_nl_clm file or the user_nl_cam file. — Reply to this email directly, view it on GitHub <#2941 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AFABYVABKN63BH35NZZDFTT2MCVHZAVCNFSM6AAAAABVT4BEKWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDMMBZGIYDOMZXGQ> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>