Diapositiva 1

1
BOLCHEM AIR QUALITY MODEL PERFORMANCE EVALUATION
OVER ITALY
Alberto Maurizi1, Mihaela Mircea1, Massimo
D'Isidoro1, Lina Vitali2, Fabio Monforti2,
Gabriele Zanini2, Francesco Tampieri1 1Istituto
di Scienze dellAtmosfera e del Clima, Consiglio
Nazionale delle Ricerche, Bologna, Italy 2ENEA -
Italian Agency for New Technologies, Energy and
the Environment, ACS-INN Section, Bologna, Italy
INTRODUCTION The geographical position and the
relief of Italy lead to very complicated
atmospheric circulation features that control the
dispersion and transport of pollutants. This work
investigates the evolution of ozone over the
whole of Italy, taking into account the Italian
and European emission inventories and the
maritime emissions , for the first time. The
study is carried out using the air quality model
BOLCHEM (Mircea et al., 2007), which comprises
the meteorological model BOLAM (Buzzi et al.,
2003), an algorithm for airborne transport and
diffusion of pollutants, and two photochemical
mechanisms SAPRC90 (Carter, 1990) and CB-IV
(Gery et al., 1989). The meteorology is coupled
on-line, one-way, with the chemistry. Thus, the
chemistry is solved simultaneously with the
meteorology, without any interpolation in time or
space, as is generally the case with the off-line
air quality models. This study was carried out
for three summer periods 1-3 June (Tuesday to
Thursday), 1-4 July (Thursday to Sunday), 5-7
August (Thursday to Saturday) and one winter
period 20-24 January (Wednesday to Sunday) during
the year 1999. The winter period serves to
understand the forecasting ability of the BOLCHEM
model at low temperatures and low actinic fluxes.
MODEL VALIDATION RESULTS The figures 1 and 2
show the surface ozone concentrations (?g/m3)
calculated with BOLCHEM at 12 UTC (14 local time
during summer) using both CB-IV and SAPRC90, for
2 June 1999. The structure of the fields reveals
that high levels of ozone are reached not only
around the city of Milan, but also around the
cities of Rome, Naples, Cagliari in the
north-east areas, from Trieste to Venice in the
north-west coasts, from Genoa to Pisa in the
south-east of Sicily, from Siracusa to Strait of
Messina and in the Gulf of Taranto, sometimes
extending up to Brindisi and Bari.
Figure 2
Figure 1
The map shows the stations used for the
evaluation of model performance. The stations
belongs to four monitoring networks BRACE, EMEP,
and the Regional Networks of Tuscany and Lombardy.
Figures A and B show the surface ozone
concentrations simulated with SAPRC90 (green
line) and CB-IV (red line) photochemical
mechanisms and the observed surface ozone
concentrations (black line with bullets) at the
stations Montelibretti (upper panels), Ispra
(middle panels) and Motta Visconti (lower
panels)(Figure A) Ferrara (upper panels),
Gambara (middle panels) and Fontechiari (lower
pannels) (Figure B)? The agreement between
simulated and measured ozone concentrations is
good for most of the stations both summer and
winter, if the ozone concentrations are not too
low (below 20 ?g/m3).
Figure B
Figure A
Quantitative model performance statistics for
hourly surface ozone over the whole domain during
summer. MNBE and MANGE were calculated with
40ppb cutoff to the ozone concentrations.
CONCLUSIONS The model performances are better
during summer, when the photochemistry is active,
than during winter. During summer, the validation
exercise shows that the model configured with
SAPRC90 always meet the US-EPA criteria for UPA,
MNBE and MANGE, while the MNBE calculated with
CB-IV ozone concentration is sometimes higher
than the recommended values.
ACKNOWLEDGEMENTS This work was conducted in the
frame of ACCENT and GEMS EC projects, Italian
MIUR project AEROCLOUDS, and was also supported
by the Italian Ministry of Environment through
the Program Italy-USA Cooperation on Science and
Technology of Climate Change.
US-EPA criteria MNBE lt 15 MANGE lt 30-35
UPA lt 20.

• REFERENCES
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