Create New case using codebase cesm2_1_3_MEGAN turned ON

[Hemraj]

Dear Scientists and all,
I can create the case without turning on the MEGAN, but when I turn ON the MEGAN (./xmlchange --append CLM_BLDNML_OPTS="-megan"), it results in some error message (ERROR: incompatible settings in drv_flds_in) (attachment). Following are the major settings of my model simulations:
codebase=cesm2_1_3
compset=FC2010climo
resolution=f09_f09_mg17
./xmlchange CLM_BLDNML_OPTS="-bgc sp" (#problem is same with bgc bgc)
./xmlchange --append CLM_BLDNML_OPTS="-megan"


Could anyone suggest to me why this error while turning on the Megan? How can it be resolved?
Thank you

 

[oleson]

I think that in this compset, CAM turns on megan, so no need to turn it on from the CLM side (and there seem to be incompatibilities in the generated namelists).
There should be something like this in drv_flds_in if megan is on:

&megan_emis_nl
megan_factors_file = '/glade/p/cesmdata/cseg/inputdata/atm/cam/chem/trop_mozart/emis/megan21_emis_factors_78pft_c20161108.nc'
megan_mapped_emisfctrs = .false.
megan_specifier = 'ISOP = isoprene',
'MTERP = pinene_a + carene_3 + thujene_a + 2met_styrene + cymene_p + cymene_o + terpinolene + bornene + fenchene_a + ocimene_al + pinene_b + sabinene + camphene + limonene + phellandrene_a + terpinene_g + terpinene_a + phellandrene_b + myrcene + ocimene_t_b + ocimene_c_b',
'BCARY = caryophyllene_b + bergamotene_a + bisabolene_b + farnescene_b + humulene_a',
'CH3OH = methanol', 'C2H5OH = ethanol', 'CH2O = formaldehyde',
'CH3CHO = acetaldehyde', 'CH3COOH = acetic_acid', 'CH3COCH3 = acetone',
'HCOOH = formic_acid', 'HCN = hydrogen_cyanide', 'CO = carbon_monoxide',
'C2H6 = ethane', 'C2H4 = ethene', 'C3H8 = propane', 'C3H6 = propene',
'BIGALK = pentane + hexane + heptane + tricyclene', 'BIGENE = butene',
'TOLUENE = toluene'
/

 

[Hemraj]

Dear @oleson,
Thank you so much. I can find something similar you mentioned in drv_flds_in inside $CaseDir/CaseDoc/drv_flds_in or in $CaseDir/Buildconf/camconf/drv_flds_in (NOT in $$CaseDir/Buildconf/clmconf/drv_flds_in), which means megan is from CAM.

But, I am confused, when I am looking for biogenic volatile organic compounds (BVOCs like isoprene emission), which is solely a part of CLM, can MEGAN coming from CAM represent BVOCs? I just want to make sure before starting the model simulation.

Many thanks!

 

[oleson]

According to the technical note:

MEGAN2.1 now describes the emissions of speciated monoterpenes, sesquiterpenes, oxygenated VOCs as well as isoprene. A flexible scheme has been implemented in the CLM to specify a subset of emissions. This allows for additional flexibility in grouping chemical compounds to form the lumped species frequently used in atmospheric chemistry. The mapping or grouping is therefore defined through a namelist parameter in drv_flds_in, e.g. megan_specifier = ’ISOP = isoprene’, ’BIGALK = pentane + hexane + heptane + tricyclene’.

The BVOCs are calculated in CLM in VOCEmissionMod.F90. So I think it's just that the species are grouped according the namelist parameter in drv_flds_in. And the emissions factors file specified in drv_flds_in is read in by CLM.

There should be BVOC output in the CLM history output of the form MEG_* (e.g., MEG_isoprene).

But honestly you could probably get a better explanation of how this works from the chemists. So you might also post your question in the CAM-Chem Forum.