BIOG and AROM in SpecDef of saprc07

CMAQ
1

BIOG and AROM are used to calculate VOC in saprc07, but i can’t find them in SpecDef file.

2

Hi Jiang,
Those definitions are out of date but BIOG is likely isoprene, terpenes, and/or sesquiterpenes.

What do you want to do with “VOC”? If you want it to be total atmospheric gaseous organic carbon, I would go through the GC.nml and include all reactive carbon-containing species. If you want it to be emitted VOCs, then I would include all organics from the EmisCtrl* file that are emitted. If you want to compare to AQS NMOC, you may need to consider a volatility and/or O:C cutoff in your definition of “VOC”. If you want the regulatory definition of “VOC” you should check 40 CFR 51.100 (40 CFR § 51.100 - Definitions. | CFR | US Law | LII / Legal Information Institute) and remove exempt VOCs like acetone and ethane.

The files may be updated in the next CMAQ release (VOC will be deprecated in the CRACMM mechanism SpecDef in favor of GROC, or gaseous reactive organic carbon, defined as all gas-phase reactive organic carbon regardless of volatility, O:C, or exempt status).
Havala

1 Like
3

If you do update the SpecDef, please post the update here and the CMAQ team can include it in the next release.

4

i’ve updated VOC in SpecDef file as :
1000.*(3.*ACETONE[1]+2.*ACETYLENE[1]+3.*ACROLEIN[1]+
4.*BACL[1]+4.*BUTADIENE13[1]+2.*CCHO[1]+7.*CRES[1]+
2.*ETHENE[1]+2.ETOH[1]+2GLY[1]+HCHO[1]+4.*MEK[1]+
MEOH[1]+3.*MGLY[1]+4.*MVK[1]+5.*OLE1[1]+5.*OLE2[1]+
6.*PRD2[1]+3.*PROPENE[1]+3.RCHO[1]+6.0RNO3[1]+
7.*TOLUENE[1]+10.*NAPHTHAL[1]+6.*BENZENE[1]+5.ISOPRENE[1])+
10TERPTOT[0]+8.*XTL[0]+ALK[0]+ACIDS[0]

TOLUENE, NAPHTHAL, BENZENE, ISOPRENE, TERPTOT, XYL are added.

I also noticed mol-weight of NAPHTHAL may be wrong in GC_saprc07tc_ae6_aq.nml.
(128.2 rather than 118.7 ?)

5

You can follow Havala’s suggestions.

Here are the definitions of BIOG and AROM if you still need them:

BIOG ,ppbC ,1000.0 * ( 5.0IPRD[1] + 4.0MACR[1] + 5.0ISOPRENE[1] + 10.0APIN[1] + 10.0TERP[1] + 15.0SESQ[1] )

AROM ,ppbC ,1000.0 * ( 6.0NPHE[1] + 7.0CRES[1] + 7.0BALD[1] + 6.0BENZENE[1] + 7.0TOLUENE[1] + 8.0MXYL[1] + 8.0OXYL[1] + 8.0PXYL[1] + 7.0ARO[1] + 8.0ARO2MN[1] + 10.0*NAPHTHAL[1] )

Please note that CRES is included in AROM; so you can remove CRES from VOC definition. Otherwise, it will be double counted.

Thanks.