Heterogeneous production of HONO

CMAQ
1

Hi all,
I would like to ask where I can find the code for parameterizations of heterogeneous production of HONO under CCTM/src/aero/aero6.
As stated by CMAQ User Guide, “In CMAQ, HONO is produced from emissions, gas-phase chemical reactions, and a heterogenous reaction on aerosol and ground surfaces. The contribution of emissions to HONO production is accounted for by including HONO emissions estimates from certain combustion sources. Each gas-phase chemical mechanism contains several gas-phase chemical reactions which also contributes to the HONO production. The heterogeneous production of HONO from the interaction of NO2 on aerosol surface is accounted for by including a heterogeneous reaction in the chemical mechanism. The heterogeneous production of HONO from the interaction of NO2 on ground surface is included in the air-surface exchange calculation and is controlled by the flag.”
Following the guideline, I tried to locate the heterogeneous production of HONO in AEROSOL_CHEMISTRY.F but was not able to find it. Could you please tell me the modules and related Fortran files for heterogeneous production of HONO from the interaction of NO2 on aerosol surface in CMAQ source code?
Any comments are highly appreciated!
@Ben_Murphy
@hogrefe.christian
@gsarwar
Thanks!
Ryan

2

Hello Ryan

@gsarwar is the correct person to tag for this question. I know there is some code related to the heterogeneous production of HONO in the vdiffacmx.F portion of both M3Dry and STAGE vdiff (here and here), but there very well might be more to it than that.

Christian

3

Dear Kai Wu,

Thanks for contacting me about HONO chemistry in CMAQ.

Gas-phase chemical reactions are included in “mech.def”, heterogeneous chemistry on aerosols is included in “mech.def” and “AEROSOL_CHEMISTRY.F”, and heterogeneous chemistry on ground is included in “vdiffacmx.F“. HONO emissions are included in emission file (GC_cb6*_ae7_aq.nml).

Thanks,
Sarwar