Long range transport of PAHs and definition of
computational domains for Rome city
simulations
Sandro Finardi, Matteo Costa e Camillo Silibello
Final version, 22/07/2011
LIFE+ Project EXPAH Action 4.2
Introduction (1)
The main processes governing determining POPs lifetime in the
atmosphere are atmospheric transport, gas-particle partitioning,
degradation and deposition.
The lifetime of atmospheric B(a)P is somewhere between a few
hours in highly polluted areas in summer and several days in
background atmosphere, where it is closely connected to the
lifetime of aerosol particles (Matthias et ale, 2009).
The environmental persistence of PAHs makes long-range
transport an important pathway for human exposure.
The computational domain extension has to be large enough to
account remote sources contribution.
European scale model simulations
European simulations show high B(a)P concentrations over Italy, with maximum
areas located over the Po Valley, Rome and Naples conurbations, and Taranto
area.
Annual mean B(a)P concentrations
(ng/m3) calculated for 2005 by EMEP
model (Gusev et al., 2007).
Annual mean B(a)P concentrations for
2001 (ng/m3) simulated by CMAQ-PAH
extension (Matthias et al., 2009).
B[a]P import in Italy
From EMEP evaluations (Gusev et al., 2007) 20% of B(a)P annual deposition over
Italy is due to transboundary transport from foreign emissions.
Contributions of transboundary transport to total annual depositions of B[a]P from
European emission sources for each European country in 2005 (Gusev et al., 2007).
Contribution of foreign sources to import
B[a]P deposition in Italy
From http://www.msceast.org/countries/Italy/index.html
Introduction (2)
Results of European scale simulations allow to identify Rome
conurbation as one of the area affected by higher B[a]P
concentrations in Western Europe
The overall contribution to B[a]P deposition over Italy from
foreign sources is around 20%, while large fraction of the country
receive larger contributions up to 30% near northern borders.
The availability of preliminary results of national scale POPs
simulations (including PAHs) from the national project MINNI
(http://www.minni.org) offered the possibility to evaluate the
effect of remote sources on PAHs concentrations in Rome and
Lazio Region.
Outline
MINNI simulations and products description
Evaluation of foreign PAH emissions on concentrations over Italy
and Lazio Region from MINNI 2005 simulations
Definition of computational domain and model simulation
configuration for EXPAH year long PAH simulations
MINNI simulations features
METEOROLOGY:
1999, 2005:
20km res. RAMS (nudging)
4km res. LAPS (diagnostic)
2003, 2007:
RAMS (nudging) with 20km
and 4km res. Two-way nesting.
AIR QUALITY:
20km & 4 km res. FARM
One-way nested
EMISSIONS:
ISPRA 2005 top-down
national inventory + EMEP
0
BC:
EMEP concentration fields
500000
1000000
1500000
500000
Available MINNI Products
• Gridded emission fields
• 3D Meteorological fields
• 3D Concentration fields of major
pollutants
000000
500000
000000
• Years: 1999, 2005, 2003, 2007
• Time resolution: 1 hour
• Space resolution: 20, 4 km
• Vertical grid:
• 12 levs (up to 4 km) 1999
• 16 levs (up to 10 km) 2005,
2003, 2007
MINNI POPs & metals
Heavy metals,Dioxins, Furans,
PAHs
• PAH congeners:
• benzo(a)pyrene
• benzo(b)fluoranthene
• benzo(k)fluoranthene
• indeno(1,2,3-cd)pyrene
• Year: 2005
• Time resolution: 1 hour
• Space resolution: 20
• Vertical grid: 16 levs (up to 10
km)
PAH long range transport
MINNI simulations for year 2005 allowed a preliminary evaluation
of foreign PAH emissions impact over Italy & Lazio Region
Model runs with full emissions and “Italy only” (no foreign
emissions and zero boundary concentration) has been used for
the analysis
Contribution attributable
to foreign emissions has been
computed in concentration and percentage
MINNI 2005 simulations:
yearly average contribution of
BC and foreign sources
PAH concentration (ng/m3)
MINNI 2005 simulations:
yearly average contribution of
BC and foreign sources
% contribution to PAH concentration
MINNI 2005 simulations:
Max hourly contribution of BC and foreign sources
PAH concentration (ug/m3)
PAH long range contribution
Long range contribution to PAH yearly average concentration is
estimated up to 0.4 ng/m3 over Italy and in the range 0.1-0.3
ng/m3 within Lazio Region
In term of percentage, the long range transport contributes to
less than 10% of concentrations over Rome urban area and up to
more than 30% on the Apennine region and in Rieti Province
The maximum impact of long range transport during episodes is
estimated to be about 2 ng/m3 of hourly average concentration
PAH modelling
Coherently with results published in recent literature the
preliminary evaluation of PAH long range transport impact shows
that it cannot be neglected
Reference model simulations integrating European and Italian
PAH emissions characterized by horizontal space resolutions in
the range 10-20 km are not available for year 2011 for their
possible use as boundary conditions over limited extension areas
(e.g. Lazio Region).
EXPAH simulations need to cover different scales, from national
to urban, to keep into account the different possible
contributions.
Different PAHs emission inventories at different scales have to be
used
EXPAH air quality computational domains
• Space resolution: 12, 4 , 1 km
• Vertical grid:
• 16 levs (up to 10 km)
• PAH inventories:
• TNO – Europe
• ISPRA – Italy
• INCOM – Italy for Lazio
and Rome
EXPAH: national scale computational
domains for national scale simulations
RAMS
Grid 1
Grid 2
∆xy (km)
48
12
Nx
90
122
Ny
78
134
Nz
35
35
FARM
Grid 1
Grid 2
∆xy (km)
48
12
Nx
81
108
Ny
69
124
Nz
16
16
EXPAH: Lazio/Rome computational domains
4800000
5200000
Grid 2
4750000
5000000
4700000
4650000
Grid 3
4800000
Grid 4
4600000
4600000
4550000
4400000
4500000
600000 650000 700000 750000 800000 850000 900000 950000 1000000
4200000
RAMS (Rot. Polar Stereo)
4000000
FARM (UTM32)
200000
400000
600000
800000
1000000 1200000 1400000
RAMS
Grid 1
Grid 2
Grid 3
Grid 4
∆xy (km)
32
16
4
1
Nx
54
58
66
70
Ny
54
58
58
70
Nz
32
32
32
32
FARM
Grid 3
Grid 4
∆xy (km)
4
1
Nx
61
60
Ny
51
60
Nz
16
16
Modelling system conceptual scheme
Synoptic meteorological
forecast (NCEP)
Meteorological Input
Meteo obs.
RAMS
Gap
SurfPRO
Goegraphic Data
Emission Input
4670000
4660000
4650000
4640000
4630000
4620000
760000
780000
800000
820000
EMMA
FARM
Emission Data
Concentration
fields
National scale air quality
forecas
Air Quality
observations
Conclusions (1)
A national scale simulation with horizontal resolution of 12 km will be
performed for the whole year 2011 to provide boundary conditions
(BC) over Lazio Region area.
• This model configuration corresponds to the national scale air quality
forecast system described in Kukkonen et al. (2011), whose results
are published at the URL http://www.aria-net.eu/QualeAria/
• The national scale simulation will not use data assimilation and will
be performed with two different configurations of FARM model: a) full
chemistry (SAPRC99+AERO3); b) PAH simulation. Results of both
simulations will be used to provide BCs for local scale simulations.
• The national scale simulation results will be preliminary evaluated
over Rome area to identify possible biases to be managed before
running the high resolution simulation
Conclusions (2)
• A local scale simulation with horizontal resolution of 4 km over Lazio
Region and 1 km over Rome conurbation will be performed for the
whole year 2011 with FARM model in PAH configuration.
• The local scale meteorological simulation will employ data
assimilation using observations collected within EXPAH campaign.
References
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Emissions of persistent organic pollutants and eight candidate POPs from UNECE–Europe in
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UNECE POP protocol, Atmospheric Environment, Volume 41, Issue 40, December 2007, Pages
9245-9261.
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Persistent Organic Pollutants in the Environment. EMEP Status Report 3/2007.
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M., Tarvainen, V., Boy, M., Peuch, V.-H., Poupkou, A., Kioutsioukis, I., Finardi, S., Sofiev, M.,
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K. (2010) Persistent Organic Pollutants in the Environment. EMEP Status Report 3/2010.