Photochemical and aerosol pollution of the environment in the regional and global scales accounting...

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

email: aloyan@inm.ras.ru

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.

H, y)(x,

~-H

y)(x,~

-z ,yy ,xx

e- Model

uubqT

ec

z

e

zz

q

zz

v

z

ueu

t

e

222

grad

ezzz

q

zz

v

z

u

eu

t b

2

32

22

1grad

2e

)(

)(

T1 =1.4, 2 = 0.7, 3 = 1.9, b = 0.7, = 0.08, = 1.1

Initial and boundary conditions

),( ),,( 002 huhuee uzz

e

x x 0 0,

e

y y 0 0,

e = 0, = 0 t = 0 и z = H ,

x = X

y = Y

Pollution Transport

Where Ci (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)

;3

3332

2221

111 x

cK

xx

cK

xx

cK

x

P P PFx

Cu

t

C

iii

photi

condi

nucli

gasi

j

ij

i

.

)(

333

3222

2111

1

3

xK

xxK

xxK

x

P P PFx

wut

kkk

coagk

condk

nuclk

aerk

j

kgjj

k

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 Pv we have a binary cluster consisting of nw water molecules and na acid molecules with mole fractions xiv(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; Pv; xil) - iv(T; Pv; xiv), il and iv are the chemical potentials in the aqueous and vapor phases, respectively, r* is the critical radius.

AnnGW aaww

)(ln

)()(2

*1,

***

xkT

xxr

freei

freei

i

)(

3

4 *2** xrw

kT

wwZJ

)2,1(exp)2,1(

*

Condensation and Coagulation

0

11

0

11 111),(

~),(

~2

1),( dgggKdgggKtgJv

gt gg

g

gggg

1exp1

8/31(4 3/1

3/1*

13/1

3/22

g

g

kTldg

gnvdv T

g

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, vg is the rate of condensation.

HG modeling domain

Nucleation rate at [H2SO4]=1.0E8 cm-3

log-scale

0.1

1

10

100

1000

10000

T=254 K T=265 K T=273 K T=281 K

J, c

m-3

s-1

RH=50

RH=70

RH=90

Nucleation rate at [H2SO4]=1.0E9 cm-3

log-scale

1.00E+00

1.00E+02

1.00E+04

1.00E+06

1.00E+08

T=254 K T=265 K T=273 K T=281 K

J, c

m-3

s-1 RH=50

RH=70

RH=90

Nucleation rate at [H2SO4]=1.0E10 cm-3

log-scale

1.00E+001.00E+021.00E+041.00E+061.00E+081.00E+101.00E+12

T=254 K T=265 K T=273 K T=281 K

J, c

m-3

s-1 RH=50

RH=70

RH=90

Nucleation rate at [H2SO4]=1.0E11 cm-3

log-scale

1.00E+001.00E+021.00E+041.00E+061.00E+081.00E+101.00E+121.00E+141.00E+16

T=254 K T=265 K T=273 K T=281 K

J, c

m-3

s-1 RH=50

RH=70

RH=90

Critical radius at [H2SO4]=1.0E8 cm-3

00.10.20.30.40.50.60.7

T=254 K T=265 K T=273 K T=281 K

r cr,

nm

RH=50

RH=70

RH=90

Critical radius at [H2SO4]=1.0E9 cm-3

0

5

10

15

20

25

T=254 K T=265 K T=273 K T=281 K

rcr,

nm RH=50

RH=70

RH=90

Critical radius at [H2SO4]=1.0E10 cm-3

0

0.1

0.2

0.3

0.4

0.5

0.6

T=254 K T=265 K T=273 K T=281 K

rcr,

nm RH=50

RH=70

RH=90

Critical radius at [H2SO4]=1.0E11 cm-3

0

0.1

0.2

0.3

0.4

0.5

T=254 K T=265 K T=273 K T=281 K

rcr,

nm RH=50

RH=70

RH=90

Threshold concentration at [H2SO4]=1.0E8 cm-3

log-scale

1.00E+00

1.00E+02

1.00E+041.00E+06

1.00E+08

1.00E+10

T=254 K T=265 K T=273 K T=281 K

Nts

h , c

m-3 RH=50

RH=70

RH=90

Threshold concentration at [H2SO4]=1.0E9 cm-3

log-scale

1.00E+00

1.00E+02

1.00E+04

1.00E+06

1.00E+08

1.00E+10

T=254 K T=265 K T=273 K T=281 K

Nts

h, c

m-3 RH=50

RH=70

RH=90

Threshold concentration at [H2SO4]=1.0E10 cm-3

log-scale

1.00E+00

1.00E+02

1.00E+04

1.00E+06

1.00E+08

1.00E+10

T=254 K T=265 K T=273 K T=281 K

Nts

h , c

m-3 RH=50

RH=70

RH=90

Threshold concentration at [H2SO4]=1.0E11 cm-3

log-scale

1.00E+00

1.00E+02

1.00E+041.00E+06

1.00E+08

1.00E+10

T=254 K T=265 K T=273 K T=281 K

Nts

h , c

m-3 RH=50

RH=70

RH=90

Concentration of H2SO4, z=6850 m, t=10 days

Nucleation rate (cm-3 s-1)

Critical radius (nm)