Geoscience Reference
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have been dedicated to the classi
cation of situations taking place in the real
atmosphere with pollutants emitted from the point sources (stacks, etc.). Suf
ciently
complete classi
cation can be found in Scorer (1997), where ten types are given of
the behavior of the pollutants
'
jet (smoke) in the vicinity of an isolated point source
(stack): folded, spiral,
flagwise; sedimenting, broadening, expanding, breaking,
bifurcational, fumigating, and rising. In each of these cases a Gauss-type model can
be used with a minimum of input information. The monitoring system should only
be able to distinguish between these situations based on measurements of meteo-
rological parameters. For instance, the folded shape of the jet can be formed due to
a rough surface (high buildings, hilly locality) in clear sunny weather. Smoke
particles are wind-driven in zig-zag inside the broadening and gradually sedi-
menting jet. The breaking jet is typical of the second half of day in summer, when
the atmosphere is well heated, and convective motions of air masses prevail.
One of the units of the atmospheric pollution model describes the process of
emission of aerosol to the atmosphere. In most cases the Gauss-type model is used:
fl
exp
r
2
2
r
M
2
Cr
ðÞ
¼f
ðÞ
;
r
ð
5
:
5
Þ
2
pr
r
where r is the distance to the center of the pollutants
˃
r
is the horizontal size of
the jet, f(h) is the vertical distribution of the mass of pollutants, M=Q
'
jet,
t is the mass
of pollutants in the jet, Q is the rate of emission from the source,
ʔ
ʔ
t is the
time step. The f function can be approximated by the following dependence: f
(h)=1/H for 0.5H < h < 1.5H and 0 in the opposite case (H is the effective height of
the jet). For instance, to calculate H, the following formula has been proposed
Despres et al. (1986):
(
29V
1
Q
1
=
2
h
Z
þ
0
:
normal conditions of stability
H ¼
49V
1
Q
0
:
29
h
Z
þ
0
:
Weak conditions of stability
flux from the source (stack), cal s
−
1
; Z is the height
where Q
h
is the rate of the heat
fl
of the source, m.
To simplify the process of simulation of the pollutants
field in the zone of the
source, the
flux can be quantized into individual formations (small clouds, dust
masses), each being considered separately as a homogeneous cloud. In particular,
for quantization of the
fl
fl
flux into n parts over the time
D
t, the following formula can
D
be used: n=2V
t/H. For instance, at the wind speed V = 5 m/s and Z = 100 m we
obtain that some clusters can be emitted from the stack every 10 s. As a result, the
process of simulating the dynamics of the whole emitted jet is much simpli
ed. So,
for instance, in modeling the propagation of sulphur one can additionally distin-
guish between sulphur-forming components.
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