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result of their warming due to solar radiation absorption) by shares of degree with
respect to the environment, which leads to an increase of water vapor pressure on
droplets and limits an activation caused by most strongly absorbing CCN.
In connection with this, it has been proposed to generalize the K
hler theory
which determines the dependence of the equilibrium water vapor pressure on the
level of water assimilation, with the size of CCN and the share of BC taken into
account. This dependence manifests itself most clearly in case of CCN with the
volume of BC greater than a sphere with D = 500 nm. In the presence of aerosol
with a relative content of BC by mass less than 10 % (per each particle), a 10 %
decrease of CCN number density can occur due to a solar warming, with a 0.01 %
level of critical oversaturation. On the other hand, the effect of warming due to
absorption by BC on activation with a
ΓΆ
βˆ’
0.1 % level of critical oversaturation is
negligibly small.
Analysis of observational data has led to the conclusion about a global strato-
sphere cooling during the last decades, though the rate of cooling depended on
duration of observation series and was speci
c for various regions of the globe.
While in high latitudes of the Southern Hemisphere the cooling trend has been
observed beginning from 1980, in the Northern Hemisphere most substantial
changes took place after 1990. The common opinion about the nature of strato-
spheric cooling in the Southern Hemisphere is based on the fact that it is connected
mainly with chemically induced ozone depletion. Here a mechanism of radiative-
chemical feedback forms, since a cooling leads to ozone depletion. A quite different
situation is observed in the Northern Hemisphere, where the internally induced
climate system
s dynamics should play an important role.
Manzini et al. (2003) undertook a numerical modeling of the atmospheric cir-
culation sensitivity to ozone depletion and to the growth of GHGs concentration,
with chemical reactions in the atmosphere taken into account. With this aim in
view,
'
xed
boundary conditions for the recent past (1960) and present conditions (1990 and
2000), considering changes of GHGs concentrations, total organic chlorine and
average SST. Changes of the ozone content were calculated with simulation of
interactivity of the processes considered.
The numerical modeling results indicate a decrease of the ozone content in the
stratosphere. Under conditions of the Antarctic, in 1990 and 2000 an
three series of numerical modeling have been carried out under
”
formed, which was absent, however in 1960, as observations showed. In the
stratosphere and mesosphere, the temperature was decreasing during the whole
period under consideration, which was most clearly manifested at the level of
stratopause and in the lower stratosphere in the region of the South Pole, which
agrees with observational data. In the lower stratosphere of the Arctic, a cooling in
March (compared to 1960 conditions) was detected only from calculations for 2000.
The activity of long waves propagating in winter from the troposphere in 1960
and 2000 turned out to be comparable. This suggests the conclusion about the
contribution of ozone depletion and an increase of GHGs concentration to the
cooling taking place in the lower stratosphere of the Arctic in 1960 and 2000. The
obtained results suggest
β€œ
ozone hole
the conclusion that
the extremely low temperatures
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