Total VOC from CB6

CMAQ-DDM-3D
1

Hi,
I am currently running CMAQv5.4.0.1/HDDM with the chemistry mechanism cb6r5_ae7_aq. My objective is to calculate the sensitivity of VOCs to O3 (ozone). The VOCs included in my analysis are:

AACD, ALD2, FORM, MEOH, FACD, ALDX, ETHA, ETOH, KET, PAR, ACET, PRPA, ETHY, ETH, OLE, IOLE, ISOP, APIN, TERP, BENZENE, TOL, XYLMN, NAPH, and SESQ.

Could you please confirm if I am missing any relevant VOCs for my analysis?

Thank you.

2

Hi FengLiu,

The importance of individual VOCs is something that you will need to decided on your own in probably depends on your application and goals.

But to clarify, do you plan to calculate sensitivity of VOCs to O3 or the sensitivity of O3 to VOCs? Both are possible, but there are normally no emissions of O3, but it does exist in initial and boundary conditions for use in DDM-3D.

Sergey

3

Hi Sergey,

I intend to calculate the sensitivity of O3 to total VOCs which should be listed in sensinput.dat. In order to proceed with my CMAQ/DDM3D run using the cb6r5_ae7_aq chemistry mechanism, I have reviewed all 27 VOC species listed in CMAQv5.4/CCTM/node/BLD_CCTM_v54_DDM3D_pgi/SA_DEFN.F, as mentioned in Winston Hao’s message.
However, I have noticed that ECH4 and CO are included in the list, while AACD, FACD, and SESQ are missing. I’m curious about the presence of ECH4 and CO, as well as the absence of AACD, FACD, and SESQ.

VOC defined by SA_DEFN.F

500         !CB6R5_AE7_AQ
501         ALLOCATE( ISAM_SPEC_VOC( 2 )%LIST( 27 ) )
502         ISAM_SPEC_VOC( 2 )%LIST = (/'ALD2   ','ALDX   ','ETH    ',
503      &          'ETHA   ','ETOH   ','FORM   ','IOLE   ','ISOP   ',
504      &          'MEOH   ','OLE    ','PAR    ','TERP   ','TOL    ',
505      &          'XYLMN  ','NAPH   ','ETHY   ','PRPA   ','ACET   ',
506      &          'KET    ','GLY    ','BENZENE','GLYD   ','MEPX   ',
507      &          'APIN   ','SOAALK ','ECH4   ','CO     '/)

Thanks.

4

That list is for use in CMAQ ISAM for a specific chemical mechanism. The list was populated manually mainly taking into account ozone production considerations. CO was added because it was important for this purpose. I honestly don’t remember why the others were omitted, and it could be a mistake.

Still, you as a user need to decide on your own what you consider to be a “VOC” for your application.

Sergey

5

Hi Sergey,

Thank you for your response. I appreciate it. You are correct that the species of volatile organic compound (VOC) components depend on specific chemical mechanisms. Carbon monoxide (CO) is considered an ozone precursor, but it is not classified as a VOC species. Similarly, ethane (ECH4) is also not considered a VOC species.

In a specific chemical mechanism, there should be a predetermined set of VOC species included. However, the ISAM_SPEC_VOC defined in SA_DEFN.F makes me confused.

Thank you.