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The relationship between meteorological
conditions and air quality in Naples, Italy
Vincenzo Capozzi
Ph.D Student in Marine, Earth and Climate Sciences
Università degli studi di Napoli “Parthenope”
Goals/outline of the work
This work try to examine some relationship between
meteorological conditions and pollutants concentrations in Naples.
Motivation in the choise of this topic: the state of the atmosphere is one
of main factors that controls the final concentration of pollutants in a site
(Oke, 1987).
The study is focused on three main aspects:
1. Relationship between wind (speed and direction) and PM10
concentration (2002-2011 period);
2. Synoptic scale control of PM10 levels (2002-2011 period);
3. Relationship between Ozone (O3) concentration and solar radiation
(2003-2011 period).
Relationship between wind conditions and
pollutants concentration in Naples (1)
PM10
daily
data
were
retrieved
from
BRACE
database
(http://www.brace.sinanet.apat.it) and cover the 2002-2011 period, unfortunately with
many gaps. The air quality monitoring stations used are:
1) Napoli Ente Ferrovie (40°51’13’’N 14°16’18’’E, 13 m asl), which is part of
A.R.P.A.C. monitoring newtork;
2) Napoli Scuola Vanvitelli (40°50’40’’N 14°13’41’’E, 190 m asl), which is part of
A.R.P.A.C. monitoring network.
Wind daily data (speed and direction) cover the 2002-2011 period and were recovered
from two weather station:
1) Napoli Capodichino (40°51’45’’N 14°17’08’’E, 88 m asl), which is part of Italian
Meteorological Service Network (www.meteoam.it);
2) Napoli Via Acton (40°50’14’’N 14°15’12’’E, 10 m asl), which is part of the DiST
(Dipartimento di Scienze e Tecnologie – Università di Napoli “Parthenope”)
meteorological network.
Relationship between wind and pollutants
concentration in Naples (2)
y = 53.94*exp(-0.1836x)
61.57*exp(-0.2187x)
R2 = 0.13
0.14
Relationship between wind and pollutants
concentration in Naples (3)
Wind direction data were divided into 8 classes. For each class, PM10 concentration
mean value for both air quality monitoring stations was computed.
Wind direction
class (degree)
Mean PM10
(μg/m3) at
Napoli Ente
Ferrovie
Number of
events in 20022011 period
(based on
available PM10
data)
Mean PM10
(μg/m3) at
Napoli Scuola
Vanvitelli
Number of
events in 20022011 period
(based on
available PM10
data)
0-45
39.5
357
38.8
311
45-90
39.5
251
37.6
209
90-135
51.5
58
46.7
41
135-180
40.3
104
40.3
87
180-225
37.7
617
38.9
477
225-270
42.7
483
35.7
414
270-315
33.1
158
29.6
130
315-360
36.4
203
34.9
167
Synoptic scale control of PM10 levels (1)
The
map
below
was
obtained
from
NCEP/NCAR
Reanalysis
(http://www.esrl.noaa.gov/psd/data/composites/day/) and
and shows
shows the
thesea
mean
levelsea
pressure
level anomaly
pressure
observed at synoptic scale in days characterized by a PM10 value in Naples (Ente Ferrovie
station) below the 10th percentile.
Good air quality events occur when a trough is formed over the Ionio Sea. In this situation winds
from first and fourth quadrant prevail in the Campania Region and in Naples Gulf.
Synoptic scale control of PM10 levels (2)
The
map
below
was
obtained
from
NCEP/NCAR
Reanalysis
(http://www.esrl.noaa.gov/psd/data/composites/day/) and
and shows
shows the
the mean
the sea
Sea level
level pressure
anomaly observed
observed
at synoptic
at scale
synoptic
in days
scale characterized
in days characterized
by a PM10
by value
a PM10
in value
Naplesin(Ente
Naples
Ferrovie
(Ente
Ferrovieabove
station)
station)
theabove
90th percentile.
the 10th percentile.
Poor air quality events occur when a ridge is formed over central-western Mediterranean basin.
This situation results in weak pressure gradient and consequentely in low wind speed.
Relationship between Ozone concentration and
solar radiation (1)
Ozone daily time series was reconstructed means of BRACE database
(http://www.brace.sinanet.apat.it). In order to have a dataset as complete as possible,
two air quality monitoring station were used:
1) Napoli Osservatorio Astronomico (40°51’46’’N 14°15’16’’E, 145 m a.s.l.), which
is a suburban station part of A.R.P.A.C. monitoring network.
2) Napoli Ospedale Santobono (40°51’00’ N 14°13’ 51’’E, 173 m a.s.l.), which is a
urban station part of A.R.P.A.C. monitoring newtork.
Daily Solar radiation data for the 2003-2011 period were retrieved from Ischia weather
Station (40°43’N 13°52’E, 104 m a.s.l.), which is part of the DiST (Dipartimento di
Scienze e Tecnologie – Università di Napoli “Parthenope”) meteorological network.
Relationship between Ozone concentration and
solar radiation (2)
Daily Ozone concentration often exceed the 80 μg/m3 when the level of solar radiation
topped 250 W/m2.
y = 0.009963x + 39.76
R2 = 0.19
ρ = 0.43
Summary
• Wind speed explains ≈ 15% of PM10 variance in Naples, according to the data
recorded in 2002-2011 period;
• daily PM10 concentration and wind speed show and inverse correlation (ρ ≈ -0.35).
Both sites chosen for the analysis show the highest and the lowest daily PM10 value at
the lowest wind speed (< 1 m/s);
• mean daily concentration of PM10 is lower in both sites when the wind comes from
the fourth quadrant (270-360°);
• good air quality events in Naples occurr when a ciclonic circulation is present over the
Ionio Sea, while poor air quality events occurr when a ridge is formed over centralwestern Mediterranean basin;
• daily ozone concentration and solar radiation show a direct relationship (ρ = 0.43).
Critical level of O3 concentration are often exceeded when solar radiation is above 250
W/m2.
References
• Bercowicz, R., Palmgren, F., Hertel, O., Vignati, E. (1996), Using measurements of air pollution
in streets for evaluation of urban air quality – meteorological analysis and model calculations,
The Science of Total Environment, vol. 189/190, pp. 259-265.
• Katsoulis, B.D. (1996), The relationship between synoptic, mesoscale and microscale
meteorological parameters during poor air quality events in Athens, Greece, The Science of the
Total Environment, vol. 181, pp 13-24.
• Oke, T.R. (1987), Boundary layer climates, 2nd edn. Methuen, London.
• Silva Junior, R. S. da, Oliveira, M. G. L. de, Andrade, M. de F. (2009), Weekend/weekday
differences in concentrations of ozone, nox, and non-methane hydrocarbon in the metropolitan
area of São Paulo. Rev. bras. Meteorol, vol.24, n.1, pp. 100-110.
• http://www.brace.sinanet.apat.it
• http://www.meteoam.it
• http://www.tutiempo.net/en/Weather/Napoli_Capodichino/LIRN.htm