Table 2.

Modeled processes and associated rate coefficients and equations.

Process	Equations	Rate coefficients	Other information*
Gas-liquid phase transfer	$C_{\text{g},i}\stackrel{k_{\text{f}}}{\to }{C}_{\text{aq},i}$	kf = kmt,iwL	$k_{\mathrm{mt},i}\left({\mathrm{s}}^{-1}\frac{{\mathrm{vol}}_{air}}{{\mathrm{vol}}_{{\mathrm{H}}_2\mathrm{O}}}\right)={\left(\frac{r^2}{3D_{\mathrm{g},i}}+\frac{4r}{3{\overline{v}}_i{\alpha }_i}\right)}^{-1}$
Liquid-gas phase transfer	$C_{\text{aq},i}\stackrel{k_{\text{b}}}{\to }{C}_{\text{g},i}$	$k_{\mathrm{b}}=\frac{k_{\mathrm{mt},i}}{H_{T,i}RT}$	$\overline{v_i}=\sqrt{\frac{8RT}{{\mathrm{MW}}_i\pi }}$
Xion,f: Dissociation	$C_{\text{aq},i}\stackrel{k_{\text{f}}}{\to }{C}_{\mathrm{aq},i}^{-1}+H^{+}$	kb = literature value, T independent	$K_{{\mathrm{eq}}_{i,T}}=K_{{\mathrm{eq}}_{i,T_{\mathrm{ref}}}}\left[\frac{-\Delta H_{\mathrm{a}}}{R}\left(\left(\frac{1}{T}\right)-\left(\frac{1}{T_{\mathrm{ref}}}\right)\right)\right]$ Activity coefficients are rolled into the forward and backward rates as appropriate
Xion,b: Association	$C_{\text{aq},i}^{-1}+H^{+}\stackrel{k_{\text{b}}}{\to }{C}_{\text{aq},i}$	$k_{\mathrm{f}}=K_{{\mathrm{eq}}_{i,T}}{k}_{\mathrm{b}}$
Ascav: Droplet scavenging of interstitial aerosol	$C_{\mathrm{aer},i,\mathrm{akn}}\stackrel{\alpha }{\to }{C}_{\text{aq},i}$	𝛼	𝛼 is the attachment rate for interstitial aerosols, calculated external to the aqueous chemistry module according to Binkowski and Roselle (2003)
Wdep: Wet deposition	$C_{\mathrm{aq},i}\stackrel{W_{\mathrm{dep}}}{\to }{C}_{\text{WD},i}$	$W_{\mathrm{dep}}=\frac{1}{{\tau }_{\mathrm{wash}}}$	${\tau }_{\mathrm{wash}}(\mathrm{s})=\frac{{\mathrm{WT}}_{AVG}\times \mathrm{CTHK}\times 3600}{\mathrm{PRATE}},0$ where WTAVG = total liquid water content, CTHK = cloud thickness, PRATE = precipitation rate
Raq: Chemical kinetics	$C_{\mathrm{aq},1}+C_{\mathrm{aq},2}\stackrel{k_{\mathrm{rxn}}}{\to }{C}_{\mathrm{aq},3}$	krxn	Complex rate coefficients are set according to the CMAQ base mechanism (Sarwar et al., 2013; Carlton et al., 2010). While most droplet species are assumed to be well-mixed, a correction factor may be applied to account for aqueous diffusion limitations (Table S3). This correction factor, Qi, relates surface and bulk droplet concentrations. krxn,effective = krxnQi $Q_i=3\left(\frac{\coth (q_i)}{q_i}-\frac{1}{q_i^2}\right),Q_i\le 1$ $q_i=r\sqrt{\frac{k_i}{D_{\mathrm{aq},i}}}$

^*MW is the molecular weight; D_g,i is the gas-phase diffusion coefficient (m² s⁻¹); 𝛼_i is the accommodation coefficient; q_i is the diffuso-reactive parameter; D_aq,i is the aqueous-phase diffusion coefficient (m² s⁻¹); k_i is the effective first-order reaction rate of species i; r is the droplet radius (m).