Hello,
I have a question about POA species in CMAQ.
There are numerous aerosol species defined as POA, and some of them are different in volatility.
If those species are defined as POA, like SVPO1, 100% of their species are in the particulate phase? Or some of them are in the gaseous phase because of the volatility?
Hello @ganghan2000,
in terms of CMAQ cb6r5_ae7 mechanism species, only ALVPO1, ASVPO1, ASVPO2, ASVPO3, AIVPO1, APOC, and APNCOM are particulate phase primary organic aerosol species (see the definitions of APOMI and APOMJ in SpecDef_Conc_cb6r5_ae7_aq.txt and the “POA = T” entries in lines 115 - 199 of SOA_DEFN.F).
Which of these species have non-zero mass associated with them depends on the treatment of POC and PNCOM emissions in CMAQ_Control_DESID_cb6r5_ae7_aq.nml:
If the non-volatile POA approach is chosen, all emitted POC mass is assigned to model species APOC and all emitted PNCOM mass is assigned to model species APNOM.
If the semivolatile POA approach is chosen, emitted POC and PNOM mass is distributed across several aerosol and vapor phase species representing different volatility bins following the approach described in Murphy et al. (2017). In this approach, primary particle phase species ALVPO1, ASVPO1, ASVPO2, ASVPO3, and AIVPO1 have vapor phase counterparts VLVPO1, VSVPO1, VSVPO2, VSVPO3, and VIVPO1. Within the CMAQ aerosol code, these vapor-particle pairs undergo dynamic and reversible partitioning, but the aerosol phase mass associated with POA emissions is always represented by ALVPO1, ASVPO1, ASVPO2, ASVPO3, and AIVPO1.
I’m tagging @Havala.Pye to correct anything I may have gotten wrong and/or expand on this description.
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