Photochemical and aerosol pollution of the environment in the regional and global scales accounting for kinetic processes of transformation A.E.Aloyan Institute of Numerical Mathematics, RAS, Moscow, Russia

Model Structure Atmospheric Hydrodynamics Pollution Diffusion and Transport Photochemical Transformation Binary Homogeneous Nucleation Condensation/Evaporation Coagulation

Regional Model Equations of Atmospheric Hydrodynamics

Terrain-following transformation To take into account the orography here we turn from the Cartesian to the generalized (x,y,  ) system of coordinates where H is the height of the upper boundary;  (x,y) is a function describing the relief. The structure of the lower atmospheric layer is described within the Monin-Obukhov similarity theory and the Businger empirical functions. The Earth-surface temperature is determined from the turbulence energy balance equation and the equation of heat distribution in soil. The hydrodynamical model allows us to calculate the flow field and turbulence parameters necessary for the pollutant transport model.

e-  Model  1 =1.4,  2 = 0.7,  3 = 1.9,  b = 0.7,   = 0.08,   = 1.1 Initial and boundary conditions e = 0,  = 0 t = 0 и z = H, x =  X y =  Y

Pollution Transport Where C i (i = 1, …, N) and  k (k = 1, …, M) are the concentrations of gaseous species and aerosols, respectively; N and M are the numbers of gaseous components and aerosol fractions, respectively. The system of equations for the pollution transport and transformation (Aloyan, 2000; Aloyan et al., 2002)

Photochemistry The chemical mechanism used in this work is an improved version of that described in Aloyan et al. (1987) and Aloyan et al. (1995). Additional species and chemical reactions were included into the mechanism from the Carbon-Bond Mechanism (CBM-IV) (Gery et al., 1989). The reaction rate constants were taken also from (Anderson 1976; Atkinson and Lloyd, 1984). This approach allows us to describe the intermediate species in more detail, while the computational burden increases only slightly. In total, the resulting hybrid model includes a total of 44 chemical species and 204 chemical reactions. The total list of chemical species is as follows:

Модель жидкофазной химии

Nucleation (Kulmala et al., 2000, Hanna, 2002) Let in the atmsophere under temperature T and pressure P v we have a binary cluster consisting of nw water molecules and n a acid molecules with mole fractions x iv (i = w; a). The particles are also assumed to be of spherical shape and in the aqueous phase. Then, the free energy of new-particle formation in the binary mixture can be represented in the form where  G is the change in the Gibbs free energy, A is the surface area, is the surface tension,  i =  il (T; P v ; x il ) -  iv (T; P v ; x iv ),  il and  iv are the chemical potentials in the aqueous and vapor phases, respectively, r * is the critical radius.

Condensation and Coagulation The kinetic equation for the change of aerosol particle-mass distribution (Aloyan et al., 1993; Aloyan et al., 1997) where g is the particle mass, J is the nucleation rate, K is the coagulation kernel, v g is the rate of condensation.

HG modeling domain

Concentration of H 2 SO 4, z=6850 m, t=10 days

Nucleation rate (cm -3 s -1 )

Critical radius (nm)