Geoscience Reference
In-Depth Information
average), there is an increasing trend of monthly mean ozone concentration by 2
6
ppbv per year with the rate preserved till 2013. This is despite the attempts
undertaken in Europe and North America on reduction of emissions to the atmo-
sphere of chemical compounds by 8
-
10 %. Therefore local measures on the ozone
layer stabilization on a global scale have no prospects.
The ozone destruction is a complex set of photochemical reactions with par-
ticipation of the compounds of hydrogen, nitrogen, and chlorine. From the available
estimates, 50
-
70 % of ozone are destructed by nitrogen compounds, 20
30 %
—
by
-
-
oxygen O,10
by
chlorine compounds. The prevailing role of nitrogen compounds in ozone
destruction has been con
20 %
—
by water-containing particles of HO
x
, and less that 1 %
—
-
rmed for all latitudes. The equation of photochemical
equilibrium between concentrations of ozone and nitrogen oxides is [NO]
·
[O
3
]/
[NO
2
]=
ʼ
, where the equilibrium constant
ʼ
depends on the solar radiation intensity
and can range from 0 to 0.02.
There are various approaches to a parameterization of the process of formation
and destruction of the ozone layer. The complexity of derivation of the dynamic
models of the ozone cycle in the atmosphere is connected with its participation in
more than 75 chemical reactions, a qualitative and quantitative description of which
is impossible without deriving detailed models of numerous minor gas components
of the atmosphere. Nevertheless, there are empirical models of the ozone layer,
which make it possible, in the present climatic situation, to obtain adequate spatial
distributions of ozone. For instance, Bekoriukov and Fedorov (1987) derived a
simple empirical model of the total ozone content con
rmed by the observation data
for the Southern Hemisphere:
Þ
¼
X
n
X
;
P
n
ðÞ
a
n
;
m
cos m
O
3
u; k
ð
ðÞþ
a
n
;
m
sin m
ðÞ
n
m
where P
m
are non-normalized spherical functions of the n degree, of the m order,
a
n,m
and a
n,-m
are the empirical coef
cients whose values are given in Bekoryukov
and Fedorov (1987) and in Krapivin and Kondratyev (2002).
There are also static models to describe the vertical pro
le of the ozone density
distribution. One of such models is the Kruger formula:
:
M
3
O
3
ðÞ
¼51
:
4 exp
h
40
½
ð
Þ=
4
:
2
M
jC=
With the combined use of static and prognostic models it is possible to predict
the levels of O
3
concentration on a real time scale. But in this case it is necessary to
describe the photochemical reactions with other components of the atmosphere and,
to a greater extent, NO
2
taken into account (Agirre-Basurko et al. 2006). Other
models of ozone have been reviewed by Kondratyev and Varostos (2000).
The simplest dynamic model of the ozone layer can be written in the form of a
balance equation that re
ects its income-expenditure components. The ozone
supplies are replenished due to the impact of UV radiation on oxygen
H
11
¼ e
3
O
A
fl
and nitrogen dioxide H
12
¼ e
2
N
A
. The ozone layer is destructed at
Search WWH ::
Custom Search