In oduc ion
Ae osols a e emi ed in he ci y oge he wi h o he gaseous pollu an s o in e es in p ocesses such as combus ion o ossil uels by
ca s, which is he main sou ce o ai pollu ion in Ba celona (Cos a and Baldasano, 1996), o o med by gas- o-pa icle con e sion in he
a mosphe e. Assuming ha ae osols and o he pollu an s mig a e oge he om he sou ce (excep o g a i a ional se ling o coa se
ae osols), he ime e olu ion o he ae osol e ical p o iles can be used o moni o he ci cula ion o ai pollu an s wi hin he egion.
Regula ae osol backsca e measu emen s using an elas ic-backsca e lida we e pe o med since May 2000 o mo e han 2 yea s in
Ba celona (Spain), a egion wi h s ong coas al and o og aphic in luences. The e ical p o iles e ie ed in a egula schedule ha e
con i med he p esence o mul i-laye ed s uc u es o ae osols abo e he mixing laye du ing nume ous measu emen days. Ea lie
e idence o his phenomena was ound du ing an elas ic-scanning lida ield campaign in 1992 (So iano and Baldasano, 1998; So iano
e al., 2000). The analysis o he me eo ological maps o he co esponding days show a common weak synop ic si ua ion oge he wi h
an in ense sola hea ing which is ypical in summe ime a ound he egion. These me eo ological si ua ions allow he de elopmen o
mesoscale lows ela ed o he daily hea ing and cooling cycle. Laye s o m when ae osols a e injec ed om he moun ains in o he
e u n low ha comple es he sea-b eeze ci cula o y cell. The egula moni o ing o ae osols as ace s o wind mo ions oge he wi h
nume ical simula ion esul s o he Ba celona a mosphe e (Toll and Baldasano., 2000) explain he main ci cula o y pa e ns o ai
pollu an s o e he Ba celona A ea in ypical summe ime si ua ions which depend on day ime con ec i e e ical mixing, sea-b eeze
ci cula ions and moun ain-induced winds.
Ba celona is loca ed on he sho es o he
Medi e anean Sea, on he no heas e n co ne o
he Ibe ian Peninsula. I s loca ion, oge he wi h
he o og aphy su ounding he egion, con ibu es
o he complexi y o he dispe sion o pollu an s
emi ed in he egion. The o og aphy o he egion
is domina ed by ou main ea u es a anged
pa allel o he coas line: (1) he coas al plain,
which comp ises an 8-km s ip o land be ween
he sea and he i s moun ain ange and which
includes mos o he ci ies in he g ea e u ban
a ea o Ba celona; (2) he coas al moun ain ange
wi h al i udes be ween 250 and 512 m; (3) he
p e-coas al dep ession (Vallèsdep ession),
si ua ed be ween he coas al moun ain ange; and
(4) he p e-coas al moun ain ange, wi h
maximum al i udes o abou 1500 m. The e a e
wo main i e alleys in he a ea: Llob ega and
Besòs. These i e s ame he ci y and hei
espec i e alleys play an impo an ole in he
es ablishmen o ai - low pa e ns.
MULTIPLE-LAYER AEROSOL STRUCTURES OBSERVED WITHIN THE BARCELONA
AIR BASIN FROM REGULAR LIDAR MEASUREMENTS: MESOSCALE CIRCULATORY
PATTERNS OF AIR POLLUTANTS IN TYPICAL SUMMERTIME SITUATIONS
Pé ez(1), C., Baldasano(1), J.M., Sica d(2),M., Rod íguez(2), A., Ga cía-Vizcaíno(2), D.
The UPC lida sys em combines
2+1 elas ic/Raman channels plus
a scanning ea u e in o a single
po able 3-D-scanning Raman
lida (SRL) ins umen . The
ae osol elas ic-backsca e lida
sys em o he UPC Ba celona is
based on a Nd:YAG lase emi ing
a 1064 nm and 532 nm .
Regula measu emen s a e
pe o med on Monday a 14:00
LST (local sola ime) +/-1 hou
and a sunse -2h/+3h and on
Thu sday a sunse -2h/+3h
(1) Uni e si a Poli ècnica de Ca alunya (UPC). Labo a o y o En i onmen al Modelling.
(2) Uni e si a Poli ècnica de Ca alunya (UPC). Dep. o Signal Theo y and Communica ions, Lida G oup.
In o ma ion om he lida and he model simula ions a e used o
explain he ci cula o y pa e ns o ai pollu an s in he Ba celona Ai
Basin. The i s mechanism is o he ypical midday o ea ly a e noon
si ua ion (1), cha ac e ized by sea-b eeze inland lows, upslope winds
in he moun ain anges, and up- alley winds in he i e alleys.
Re u n lows om he sea-b eeze ci cula o y cell and om he
o og aphic injec ion o he moun ains o he coas al ange ake place
be ween 800-1000 m, dependen on he dep h o de elopmen o he
ci cula ion cell. The high al i ude si ua ion is domina ed by a gene al
subsidence caused by he high-p essu e a ea loca ed abo e he egion
a he synop ic scale.
The mid-a e noon si ua ion (2) also shows a gene al in low ci cula ion
ypical o he day ime pe iod. Howe e by his ime, he sea b eeze has
pene a ed o e he coas al moun ains and i s associa ed on has
eached he p e-coas al moun ain ange. A ci cula o y cell be ween he
wo moun ain anges appea s. In addi ion, e u n lows p oduced by
o og aphic injec ions o his second highe moun ain ange a e si ua ed
a highe al i udes, abo e 1500 m. Subsidence pe sis s alo .
The inal si ua ion (3) co esponds o he nigh ime egime, i.e., he
sea b eeze has e e sed and a gene al o sho e low is now p esen .
This o sho e low is cha ac e ized by he combined e ec s o land
b eeze, d ainage alley winds, and downslope winds in he moun ains.
Subsidence pe sis s on he synop ic scale, and e ec s om peninsula -
scale phenomena a e now mo e e iden . As a consequence o he
Ibe ian he mal low cen e ed on he peninsula a his ime o he yea ,
pollu an s om i s cen e ise up and hen di e ge owa d he coas
du ing nigh ime. This e u n low akes place a e en highe al i udes
(2000-4000 m) and explains ele a ed ae osol laye s imaged by he
lida du ing he nigh and ea ly mo ning scans he du ing a ypical
summe day du ing midday, a e noon and nigh pe iods.
Schema ics o he mechanisms de e mined as impo an in he de elopmen o
a mosphe ic ci cula o y pa e ns wi hin he basin o a ypical summe ime si ua ion
Co esponding au ho : José Ma ia Baldasano. Labo a o iode Modelización Ambien al. Dp . P oyec osde Ingenie ía, ETSEIB Uni e si a Poli ècnica de Ca alunya(UPC) A da. Diagonal 647, P 10, 08028 Ba celona, Spain. Phone +34 934011746. Fax +34 933340255. E-mail add ess: [email protected]
Me eo ological se ling and ypical summe ime scena ios
Concluding ema ks and u u e wo k
Acknowledgemen s
The Ba celona UPC lida
P e ious esea ch
Desc ip ion o he Ba celona A ea
Lida egula measu emen s
2001 / 07 / 02
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Backsca e (1/m s )
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13:11-13:41 UTC
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18:06-18:36 UTC
2001 / 08 / 13
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13:56-14:26 UTC
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16:28-16:58 UTC
2002/04/29
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13:28-13:58 UTC
18:51-19:21 UTC
2002/05/13
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13:42-14:12 UTC
18:37-19:07 UTC
2002 / 07 / 11
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18:12-18:42 UTC
2002 / 07 / 18
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18:31-19:01 UTC
2002 / 07 / 22
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Range co ec ed (a bi a y uni s)
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13:18-13:48 UTC
19:11-19:41 UTC
2002 / 08 / 12
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17:59-18:31 UTC
2002 / 08 / 19
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Range co ec ed (a bi a y uni s)
heigh (m)
13:54-14:24 UTC 532 nm
17:55-18:25 UTC 532 nm
2002 / 08 / 26
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Range co ec ed (a bi a y uni s)
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14:20-14:55 UTC
2002 / 08 / 29
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Range co ec ed (a bi a y uni s)
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17:59-18:29 UTC 532 nm
2001 / 06 / 19
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0123456
Backsca e (1/m s )
heigh (m)
13:34-14:04 UTC
15:41-16:11 UTC
17:28-17:58 UTC
Since May 2000 he Ba celona
lida s a ion has obse ed
nume ous ae osol e ical p o iles
p esen ing a mul i-laye ed
a angemen o ae osols. The
me eo ological si ua ion a ound
Ba celona was ypical o
summe ime o he egion wi h a
weak synop ic si ua ion abo e he
Ibe ian Peninsula. The igu es on
he igh show lida backsca e
and ange co ec ed e ical
p o iles (a e aged o e 30
minu es) p esen ing e ical
dis ibu ions o ae osols o e he
ML in laye s o di e en heigh
and hickness. Many ae osols a e
emi ed in o he a mosphe e
du ing he mo ning. As sola
adia ion inc eases, u bulence
in ensi y inc eases and a ML
o ms. The ML o e land du ing
his ime o he yea in he
Ba celona egion g ows o a
maximum heigh o 800-1000m
a abou 13:00 LST (11:00 UTC)
(So iano e al, 2001). The heigh
o he ae osol laye s a y om
1000 o 4000m and he hickness
ange ypically om 100m o
1000m.
The weak synop ic si ua ion
(weak p essu e g adien )
oge he wi h in ense sola
hea ing allows he de elopmen
o mesoscale lows ela ed o he
daily hea ing and cooling cycle.
Laye s o m when ae osols a e
injec ed in o he e u n low ha
comple es he sea-b eeze
ci cula o y cell. As he day
p og esses and he b eeze
pene a es u he inland, he
ci cula o y cell associa ed wi h i
g ows, and i s associa ed e u n
low occu s a highe al i udes.
O og aphic injec ions o ae osols
om he su ounding moun ains
a e added o his e u n low.
The Ibe ian Medi e anean coas p esen s di e en ia ed me eo ological ea u es om he cen al and no he n egions o Eu ope
and om he A lan ic Ibe ian egions, de i ed om i s loca ion wi h espec o he su ounding me eo ological synop ic sys ems,
he complex o og aphy o he egion and a high deg ee o insola ion and sca ce ain all. The me eo ology and he o igin o he ai
masses a i ing a he Ibe ian Peninsula a e highly in luenced by he Azo es high p essu e sys em ha is loca ed o e he A lan ic
Ocean and ha in ensi ies du ing he wa m season. F om sp ing o au umn, ba ome ic swamps o an icyclonic si ua ions wi h
weak p essu e g adien s occu all o e he egion.
Unde his low p essu e ho izon al g adien
scena ios, sea b eeze and mon ain induced
winds p edomina e in such a way ha pollu an s
a e e-ci cula ed and pollu ed a mosphe ic laye s
a e de eloped a se e al heigh s.
I adiance p o ile
Re e ences
So iano e al. (1998, 2000) s udied he ci cula o y
pa e ns o ai pollu an s in he a ea o Ba celona
wi h bo h lida da a and nume ical simula ion.
Ve ical lida scans we e pe o med unde a weak
synop ic si ua ion on he pe iod 26-28 July 1992
and e ealed a mul ilaye a angemen o
pollu an s o e Ba celona. Toll and Baldasano
(2000) chose he 5 Augus 1990 wi h simila
synop ic condi ions o model pho ochemical ai
pollu ion in he Ba celona a ea. In ac , he highes
le els o pollu an s in he egion a e usually
eached in summe ime unde weak p essu e
g adien condi ions. The simula ion esul s, om
bo h me eo ological and pho ochemical dispe sion
modules, we e compa ed wi h measu emen s om
su ace s a ions, and p o ed o be ai ly simila .
The esul s show uppe ai laye s o O3caused by
he ein o cemen o he sea b eeze in he coas al
ange (upslope winds) ha injec s g ound ai
masses owa ds uppe laye s o he PBL. No
measu emen da a we e a ailable o e alua e he
model in he uppe ai laye s. Milláne al. (1997)
ha e also epo ed he p esence o uppe ai
pollu ed masses in eas e n Spain.
subsidence
Upslope winds
Re u n lows
800-1000m
Sea b eeze
Medi e anean
Sea
Ba celona
ci y Coas al
ange P e-coas al
dep ession P e-coas al
ange
subsidence Re u n lows
> 1500 m
Sea b eeze
Medi e anean
Sea
Ba celona
ci y Coas al
ange P e-coas al
dep ession P e-coas al
ange
subsidence
Downslope winds
Peninsula scale
Re u n lows
Land b eeze
Medi e anean
Sea
Ba celona
ci y Coas al
ange P e-coas al
dep ession
P e-coas al
ange
midday o ea ly a e noon
a e noon
nigh
1
2
3
0
100
200
300
400
500
600
700
800
1000
1100
CORREDOR
GARRAF
COLLSEROLA
ST. LLORENÇ
del Mun
MONTSERRAT
MEDIONA
MONTSENY
Medi e anean Sea
Vallès dep ession
PENEDÈS
Heigh (m)
Anoia alley
Llob ega
alley
Besós alley
Ba celona
Coas al Dep ession
x ?lida loca ion
Ve ical lida scans 26
July 1992 (So ianoe
al., 2000)
Pho ochemical dispe sion simula ion o he Ba celona
A ea he 5 Augus 1990 (Toll and Baldasano, 2000)
Cos a, M. and Baldasano, J. M.: 1996, ‘De elopmen o a Sou ce Emission Model o A mosphe ic Pollu an s in he Ba celona
A ea ’, A mos . En i on. 30A , 309–318.
Millán, M., Sal ado , R., and Man illa, E.: 1997, ‘Pho ooxidan Dynamics in he Medi e anean Basin in Summe : Resul s om
Eu opean Resea ch P ojec s’, J. Geophys . Res. 102, 8811–8823.
So iano, C. and Baldasano, J. M.: 1998, S udy o he Land-Sea In e ace in he Ba celona A ea wi h Lida Da a and Me eo ological
Models, in C. A. B ebbia (ed.), En i onmen al Coas al Regions, Compu a ional Mechanics Publica ions, pp. 135–142.
So iano, C., Baldasano, J.M., Bu le , W.T. and Moo e, K. (2000) Ci cula o y Pa e ns o Ai Pollu an s wi hin he Ba celona Ai
Basin in a Summe ime si ua ion: Lida and Nume ical App oaches . Bounda y-Laye Me eo ology, 98, 1: 33-55
Toll I. and J.M. Baldasano(2000) Pho ochemical Modeling o he Ba celona A ea wi h Highly Disagg ega ed An h opogenic and
Biogenic Emissions. A mosphe ic En i onmen , 34, 19: 3069-3084.
This wo k was suppo ed by he
EARLINET p ojec om he
Eu opean Commission unde
g an EVR1-CT1999-40003 and
he p ojec s IMMPACTE and
CICYT REN2000 -1754-C02
ESA is also hanked o he
ex e nal pos doc o al ellowship
alloca ed oM. Sica d.
We acknowledge he NOAA Ai
Ressou ces Labo a o y o
p o iding he me eo ological
maps.
Mesoscale ci cula o y pa e ns a e mainly de e mined by he o og aphy o he egion. The lida p o iles om a la ge
measu emen pe iod (may 2000 –decembe 2002) in he ame o EARLINET ha e shown a mul ilaye a angemen o
ae osols o e he Ba celona egion du ing ypical summe ime si ua ions in he absence o la ge scale o cing. This was
p e iously obse ed in o he wo ks by lida echniques and nume ical app oach (Toll and Baldasano, 2000; So iano e al
2000). The combina ion o lida da a wi h me eo ological mesoscale models p o ides an explana ion o he ci cula o y
pa e ns o pollu an s wi hin he Ba celona ai basin and demons a es i s sui abili y o s udy a mosphe ic ci cula ions and
bounda y laye s uc u e a a egional o local scale.
Fu u e measu emen s will be pe o med wi h he ecen ly upg aded UPC lida sys em, in eg a ing a Raman channel and
scanning capabili ies, in o de o quan i a i ely e ie e op ical p ope ies o he ae osol laye s and deepen in he
comp ehension o he anspo pa e ns o pollu an s wi hin he egion.
Labo a o io de
Modelización Ambien al
Ba ome ic
swamp