Geoscience Reference
In-Depth Information
Denote as C
s
ð
t
; u; k;
h
Þ
the concentration of aerosol of the s-th type at the height
h over the point with coordinates (
) at a time moment t. For the Euler-type
model, general equations of aerosol transport in the environment according to (
5.3
)
have the following form:
ˆ
,
ʻ
þ
@
@
y
@
@
t
þ
V
u
@
C
s
C
s
@u
þ
V
k
@
@
y
þ
V
h
@
C
s
@
h
¼
@
C
s
K
u
@
C
s
@u
K
k
@
C
s
@k
@u
þ
E
s
t
þ
@
@
K
h
@
C
s
@
ð
; u; k;
h
Þ
h
h
v
1s
v
2s
þ
P
s
C
1
; ...;
C
q
where K
ˆ
, K
ʻ
, and K
h
are coef
cients of the turbulent diffusion, E
s
is the charac-
teristic function of the sources of emission of aerosols of the s-th type, P
s
is the
operator describing physical and chemical transformations of aerosol, v
1s
is the rate
of aerosol washing out with precipitation, v
2s
is the rate of dry deposition, V ¼
f
V
u
;
V
h
g
are the wind speed components.
The model of this type is used to calculate the aerosol concentration in the
atmosphere, as a rule, for the scales of territory exceeding 50 km. Simpli
V
k
;
ed
schemes of calculation of the C function are drawn by dividing the space into units
Du Dk D
h, and at each height h
k
a step-by-step calculation of concentration
is made. The calculation scheme can be further simpli
C
s
t
ed by
dividing the procedure into two stages. First, for each level of the vertical digiti-
zation of space the distribution of C
s
t
; u
i
; k
j
;
h
k
h
k
and then the processes of the
vertical transition of aerosols is taken into account. This scheme enables one to
easily move on to vertically averaged levels depending on available information
about the parameters of the atmospheric vertical strati
; u
i
; k
j
;
cation. Convergence of such
a procedure depends on relationships between the parameters
h.
The Euler-type model contains many degrees of freedom including the consid-
eration of various scenarios. The base of knowledge of the simulation system (the
description of ESPAP is given below) contains sets of parameterizations of partial
processes of aerosol transformation, and a concrete choice is made by the user.
Information in data and knowledge bases are structured according to a multitude of
spatial and object identi
D
t
; Du; Dk; D
ers
—
matrix structures {A
m
}. In particular, in the
“
default
mode
regime the following parameterizations are used.
In accordance with the structure of the identi
”
er describing the sources of pol-
lution, in each compartment
the passport information about the rates of
emission of the s-th pollutant is put in: minimum and maximum rates E
s,min
and E
s,
max
, respectively. In the absence of additional information about some source, the E
s
value is calculated according to the procedure of the uniform distribution over the
interval [E
s,min
,E
s,max
] or another law of distribution is assumed (e.g., the Gauss law).
The functional description for v
1s
and v
2s
is important, and the model
ʔˆ × ʔʻ
s adequacy
depends on it. Therefore, many studies have been dedicated to this problem. It has
been proven that the following linear approximation of the functions v
1s
and v
2s
is
most acceptable:
'
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