Hi forum,
It's not clear to me how the reaction rate of SO2 (gas) + OH -> H2SO4 (gas) is calculated in CAM6. The equation report in chem_mech.doc gives this reaction as d(H2SO4)/dt = r3*OH*SO2. When looking through mo_usrrxt.F90 I find this expression for the reaction rate (rxt):
which I think only depends on temperature (tinv) and atmospheric density (m). In mo_rxt_rates_conv.F90 it looks like the reaction rate is updated through
I think sol(:,:,3) refers to the volumetric mixing ratio of SO2 but I'm not sure. I'm also not sure where the concentration of OH (which is prescribed in CAM6) is taken into account. Any clarifications would be greatly appreciated.
All the best, Tomas.
It's not clear to me how the reaction rate of SO2 (gas) + OH -> H2SO4 (gas) is calculated in CAM6. The equation report in chem_mech.doc gives this reaction as d(H2SO4)/dt = r3*OH*SO2. When looking through mo_usrrxt.F90 I find this expression for the reaction rate (rxt):
Code:
!-----------------------------------------------------------------
! ... SO2 + OH --> SO4 (REFERENCE?? - not Liao)
!-----------------------------------------------------------------
if( usr_SO2_OH_ndx > 0 ) then
fc(:) = 3.0e-31_r8 *(300._r8*tinv(:))**3.3_r8
ko(:) = fc(:)*m(:,k)/(1._r8 + fc(:)*m(:,k)/1.5e-12_r8)
rxt(:,k,usr_SO2_OH_ndx) = ko(:)*.6_r8**(1._r8 + (log10(fc(:)*m(:,k)/1.5e-12_r8))**2._r8)**(-1._r8)
end ifwhich I think only depends on temperature (tinv) and atmospheric density (m). In mo_rxt_rates_conv.F90 it looks like the reaction rate is updated through
Code:
rxt_rates(:ncol,:,4) = rxt_rates(:ncol,:,4)*sol(:ncol,:,3) ! rate_const*OH*SO2I think sol(:,:,3) refers to the volumetric mixing ratio of SO2 but I'm not sure. I'm also not sure where the concentration of OH (which is prescribed in CAM6) is taken into account. Any clarifications would be greatly appreciated.
All the best, Tomas.