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model revealed, on the whole, an agreement of estimates, but the results discussed
are characterized by greater volumes of energy at high altitudes, which can partially
result from a longer integration time and lacking of consideration of the strikes onto
the Earth in the model in question, as well as from some assumptions made earlier.
On the whole, the numerical modeling of lightning formation carried out recently
and their impact on NO formation should be considered more adequate than in
previous studies. The necessity of further improvement of the model has determined
the development of a new 3D model of the processes of formation of electric
charges in thunderclouds with a more complete than earlier consideration of
chemical processes of nitrogen oxides formation under the in
fl
uence of lightning
strikes (Zhang et al. 2003b).
A totality of considered GHGs includes in this case NO, NO
2
,O
3
, CO, CH
4
,
OH, and HNO
3
. The numerical modeling has been carried out for concrete con-
ditions of thunderclouds (storm) observed on 19 July 1981 with 18 intra-cloud
strikes during 3 min. The numerical modeling has been carried out for a period of
38 min, before the thundercloud dissipated. The level of energy dissipated at
lightning strikes varied within 0.91
2.28 GJ. The maximum level of the NO
x
mixing ratio due to lightning strikes reached 35.8 ppb. At the cloud
-
s dissipation,
after cessation of lightning strikes, maximum concentrations of NO and NO
2
(in
both cases) constituted about 6.3 ppb and were observed at an altitude of about
4 km. The NO mixing ratio in an anvil reached a maximum of about 2 ppb at an
altitude of about 10.5 km. These results agree well with observational data.
Quite surprising was the formation of the NO
2
plume at a concentration of about
0.5 ppb, which reached the surface. In the case of NO there was no plume. On the
other hand, NO was transported from the cloud
'
s centre to the anvil absent in the
case of NO
2
, which was determined, probably, by the impact of photolysis. The
ratio of concentrations NO
2
/NO decreased with altitude in accordance with
observational data. The formation of NO calculated per unit
'
length averaged
10
22
molecules m
−
1
. The results obtained show that the short-lived storms
determine the formation of the vertical pro
2.03
×
le of NO
x
concentration, that differs
from the earlier observed C-shape pro
le.
Mansell et al. (2002) carried out a numerical modeling of lightning strikes with the
use of a stochastic model of dielectric break and parameterization of electri
cation
mechanisms. This model enables one to simulate a 2D development of a strike as a
stochastic
process. The strike channels propagate over a homogeneous
spatial grid, and the direction of propagation (including diagonals) for each step is
considered random with the probability of the choice of a certain direction depending
on the total electric
“
step-by-step
”
fields are calculated anew with
the use of the Poisson equation in order to take into account the impact of the
channel
field. After each step, the electric
s conductivity. The applied parameterization of the process of lightning
strikes formation, provides a realistic 3D simulation of rami
'
ed strikes. The model is
able to simulate the formation of different kinds of lightning strikes, including intra-
cloud strikes, negative and positive strikes
“
”
(CG).
According to numerical modeling results, the hypothesis that negative strikes
appear only when the region of the positive strike is located beneath the centre of
cloud-ground
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