Environmental Engineering Reference
In-Depth Information
Spray (“segr”) during the period 6-7 February 2006 are compared. Beside the
difficulty in evaluating the chemical model performances because measured and
simulated NO
x
concentrations rarely agree at the same time, it can be observed
that Spray generally reproduces the NO
x
measurements trend. However, when the
values of NO
x
are similar, the NO
2
simulated values are very close to the
NO
2
/NO
x
concentrations, concerning measured data, Spray “segr” and Spray “no
segr” simulation results, during the nocturnal hours, are depicted. As a matter of
fact, being in these cases the ozone background concentrations almost constant, the
NO
2
/NO
x
measured values depend only on the NO
x
measured values, especially
for high NO
x
values, where only the 10-20% of NO emitted has been transformed
in NO
2
due to the oxidation reaction with O
3
. The effect of the segregation
parameterization yields to a slowing down of the oxidation reaction that otherwise
would produce much more NO
2
and consequently higher NO
2
/NO
x
levels at the
station location.
300.00
250.00
200.00
Measured
Spray segr
Spray no segr
150.00
100.00
50.00
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
NO
2
/NO
x
Fig. 2.
NO
x
against NO
2
/NO
x
measured, Spray “segr”, and Spray “no segr” concentrations
during nocturnal hours
Acknowledgments
This work has been financed by the Research Fund for the Italian Electrical
System under the Contract Agreement between CESI RICERCA and the Ministry of Economic
Development - General Directorate for Energy and Mining Resources stipulated on June 21,
2007 in compliance with the Decree n.73 of June 18, 2007.
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