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An new emission An new emission model model for for rere-suspension of-suspension ofparticles along particles along roadsroads

Gunnar Omstedt*, Björn Bringfelt and Christer Johansson**

* Swedish Meteorological and Hydrological Institute** ITM Air Pollution Laboratory,Stockholm University

•introduction•description of themodel•measurements•results•sensitivity analysis•conclusions

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0 10 20 30 40 50 60 70 80 90 100

LONDON

LONDON

LONDONHELSINKI

GLASGOW

CHARLEROILONDON

MÏNCHEN

MÏNCHENZÜRICH

BREMEN

MÏNCHENMÏNCHEN

MÏNCHEN

PRAHALONDON

DARMSTADT

BERLINZÜRICH

PRAHA

BERLINMADRID

MADRID

ROSLAGSVÄGENBERLIN

MADRID

E4 SOLLENTUNAMADRID

BRATISLAVALISBOA

VALHALLAVÄGEN

PRAHAPRAHA

PRAHA

PRAHAMADRID

NORRLANDSG

PESCARAESSINGELEDEN

MADRID

SVEAVÄGENHORNSGATAN

UG/M3

Measurements from 19 countries in Europe (including more than 700 measurementsites) of PM10 halter (µg/m3) as 90-percentiles(AirBase CAFE-PM,2003)

IntroductionIntroduction

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Measured concentrations of PM10 (µg/m3) at Hornsgatan presentedas running monthly average. Red line is street level and blue line isroof level measurements. Model evaluations are done for the year2000.

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Model descriptionModel description

)(** int, dustedfe erwrefPMfq

suspensionref =−

suspensionref

directf

totf eee −+=

Processes Emissionsfactor(mg/vkm)Exhaust pipe 20Tyre and brake wear 10Road wear 10Re-suspension (dry conditions) 100-1000

Winter

Summer )(* , dustefe summerrefPMfq

suspensionref =−

fq is the source strength for re-suspension which is related to themoister amount of the dust on the street surfaced is the amount of dust on the street

)(,

dustrefPMf

e is a reference emission factor

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Model descriptionModel description

the tracer method

−−

=)(

)( 1010

,10, NOxroof

NOxstreet

PMroof

PMstreet

NOxfref

PMf CC

CCee

2-Jan 2-Mar 1-May 30-Jun 29-Aug 28-Oct 27-Dec

0

400

800

1200

1600

2000

ef(d

ust

) m

g/fk

m -

mä

tda

ta

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Model description- basic assumptionsModel description- basic assumptions

dd SiSodtdd −=)( Sources Sinks

Sanding/salting Re-suspensionTraffic related road wear Run-off with precipitation

d is the dust depot (relative units)

g (mm) is the moister amount on the surface

Sources SinksPrecipitation Run-off

Evaporationgg SiSodt

gd −=)(

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Model description- the Model description- the ffq parameter

g (mm) is the moister amount on the surface

gredrrgg *),0.1min( +=

)*exp( pEkgred −=

rr is hourly precipitationgred is hourly reduction factor for g due to evaporation

obtained by solving the budget equation:

m

p

g

mEg

dtdg )(

∗−=

where mg is maximum moisture amount and )(mE p is evaporation rate when g=gm.

Ep is evaporation; k empirical factor foundto be k=0.075

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Model description- the Model description- the ffq parameter

))1(

(*3600

a

p

an

p

rL

cerR

E

γ

γρ

γ∆+

∆+∆

=

gfq *93.01−= fq is the source strength for re-suspension

Rn is net radiation, ra aeodynamic resistance ∆e the saturated vapour pressure deficit

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Model description- the Model description- the dd parameter, sources parameter, sources

a) sanding/saltingif we have no data on sanding/salting then we assume that sanding/salting occurs during days with slippery conditions

nanskidanskidanskid /1+=

anskid is the accumulated number of days with sanding/salting during the current winter season

b) action by studded tyrestyre is the ratio of accumulated depot of material,released by friction between studded tyres andpavement, to the highest depot at the end of thewinter seasonadubb is the share of studded tyreskt is an empirical factor

1-Jan 1-Apr 30-Jun 28-Sep 27-Dec

0

0.2

0.4

0.6

0.8

1

stu

dd

ed t

yres

dubbt aktyretyre *+=

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Model description- the Model description- the dd parameter, sinks parameter, sinks

a) re-suspension

b) run-off

qsusp fdecayf *1−=fsusp is the relative hourly decay of the dust depot due to re-suspensiondecay is an empirical parameter

[ ]95.010

)2/()2(*05.0110,2

0.12

max

=>−−−=∈

=<

frfrrif

rrfrfrrif

frfrrif

ff

frf is the hourly dust depot decay factor due to run-off

For every hour anskid and tyre are reduced due to re-suspension and run-off

suspffrfanskidanskid **=suspffrftyretyre **=

)0.,1*)max(( −+= pf Errgr rf is the hourly water runoff

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Model description- the Model description- the dd parameterparameter

αresusp

anskidresusptyreresuspd ** βα +=

is the share of tyre and road particles in the total road dust depot

βresusp is corresponding share for sand/salt particles

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Model descriptionModel description

1-Jan 31-Jan 1-Mar 31-Mar 30-Apr

0.2

0.4

0.6

0.8

1

d r

elat

ive

units

tyredanskid

1-Jan 31-Jan 1-Mar 31-Mar 30-Apr 30-May

0

0.2

0.4

0.6

0.8

1

f q r

elat

ive

units

1-Jan 31-Jan 1-Mar 31-Mar 30-Apr 30-May

0

400

800

1200

e fre

susp

ensi

on

( m

g/fk

m)

a

b

c

index for rain

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HornsgatanHornsgatan, Stockholm, Stockholm40 000 v/d40 000 v/d

Figur 5. Hornsgatan monitoring station North (N) and South (S). The houses are of similarheight, 24 m, total street width is 24 m. Uphill slope westward is 2.3% (Gidhagen et al.,2004).Measurements of PM10 are only done on the north side (http://www.slb.nu/).

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NOx HornsgatanNOx Hornsgatanyearyear 2000 2000

0 200 400 600 800 1000NOxstreet-NOxroof (µg/m3)

0

200

400

600

800

1000

NO

x (µ

g/m

3 ) m

odel

- O

SP

M

averageX=155.3averageY=132.5r=0.76

Comparison of measured and modelled concentrations of NOx

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PM10 PM10 HornsgatanHornsgatanyear 2000year 2000

1-Jan 1-Mar 30-Apr 29-Jun 28-Aug 27-Oct 26-Dec

0

40

80

120

160

PM

10

stre

et-P

M1

0ro

of (

µg

/m3 )

Hornsgatan 2000daily mean

measurmentsmodel

average measurments=24.9average model=24.0r=0.77

Comparison of measured and modelled concentrations of PM10 (µg/m3) .

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PM10 PM10 HornsgatanHornsgatanyear 2000year 2000

0 20 40 60 80 100 120 140 160PM10 (µg/m3) measured-background

0

20

40

60

80

100

120

140

160

PM

10

(µ

g/m

3 ) m

od

el

measured-

background modelyearly mean 24.9 24.090-percentile 64.5 58.798-percentile 102.6 101.7

As the last figure but sorted in size

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PM 2.5 PM 2.5 HornsgatanHornsgatanyear 2000year 2000

1-Jan 1-Mar 30-Apr 29-Jun 28-Aug 27-Oct 26-Dec

0

10

20

30

PM

2.5

stre

et-P

M2

.5ro

of (

µg

/m3 )

Hornsgatan 2000daily mean

measurmentsmodel

average measurments=5.4average model=5.5r=0.72

Comparison of measured and modelled concentrations of PM2.5 (µg/m3)

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VallstanäsVallstanäs, E4:an norr om Stockholm, E4:an norr om Stockholm52 300 v/d52 300 v/d

Monitoring campain 2003 mars-maj

E1

W1

E2

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NOx VallstanäsNOx Vallstanäs

20-Mar 27-Mar 3-Apr 10-Apr 17-Apr 24-Apr 1-May 8-May 15-May

0

100

200

300

400

NO

x E1

(µg/

m3 )

Vallstanäs 2003measurmentsmodel

0

100

200

300

400

N

Ox

(µg/

m3 )

mod

elw

ind

dire

ctio

n S

SW

-NN

W

0 100 200 300 400NOxE1-NOxbackground (µg/m3)

average x=72.9average y=64.4r=0.76

Comparison of measured and modelled concentrations of NOx (µg/m3)

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PM10 PM10 VallstanäsVallstanäs

20-Mar 27-Mar 3-Apr 10-Apr 17-Apr 24-Apr 1-May 8-May 15-May

0

40

80

120

160

200

PM

10E

1-P

M10

back

grou

nd (µ

g/m

3 )

0 40 80 120 160 200PM10E1-PM10background(µg/m3)

0

40

80

120

160

200

P

M10

(µg/

m3 )

mod

el

win

d di

rect

ion

SS

W-N

NW

average x=22.9average y=22.2r=0.68

Comparison of measured and modelled concentrations of PM10 (µg/m3)

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SourceSource-receptor -receptor modellingmodelling

0

10

20

30

40

50

60

70

80

90

100

10-Mar 20-Mar 30-Mar 09-Apr 19-Apr 29-Apr 09-May 19-May 29-May

Date 2003

PM

10

µg

/m3

Traffic-related sources PM10 Model

Figure 1. Comparison between the PMF source-receptor model apportionment of PM10concentrations for the sum of the four traffic-related sources and the PM10 concentrations

estimated by the SMHI PM10 model.

Erik Swietlicki et al., 2004

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Sensitivity analysisSensitivity analysis

1-Jan 31-Jan 1-Mar 31-Mar30-Apr30-May29-Jun 29-Jul28-Aug27-Sep27-Oct26-Nov26-Dec

0

20

40

60

80

100

120

140

160

PM

10 (

µg/m

3 )

0

50

100

150

200

250

NO

x (µ

g/m

3 )

no fq or d functionsno summer sub modelmeasurments - NOxno d function no summer sub modelno summer sub modelmeasurments - PM10 complete model

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ConclutionsConclutions

• A new model for calculation of emissions from re-suspended particles (PM10 andPM2.5) in traffic environments is presented.

• The model is compared with measurements, both from a narrow street canyon inStockholm (Hornsgatan) and for an open highway, with good results.

• The model is able to account for the main features in the PM10 variability, especiallythe peak inPM10 concentrations in late winter and early spring that is commonlyexperienced in the Nordic countries where studded tires are used.

• More tests on other streets and roads need to be done

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IndataIndata

Meteorologiska data: vind, temp, fukt, nederbörd, globalstrålning, moln

Trafik data: fordonsmängd, andel tunga fordon, hastighet

Bakgrundshalter: bakgrundshalter av PM10

Geometrisk data: gatans/vägens riktning, bredd, byggnadshöjder antal körfält

Vägdata: vägbanans fuktighet, sandning/saltning, snöröjning, dubbdäcksandelar, renhållning, egenskaper hos vägbeläggning

Information som ofta saknas!

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