Refinement and evaluation of the suspension emission model

Mari KauhaniemiResearch ScientistFinnish meteorological Institute, Air Quality, Dispersion modelling

NORTRIP meeting (Arlanda)16.11.2010

Background• Based on the PM emission model developed by

Omstedt et al. (2005).

• Aim is to use it also in forecasting slightly modified.

• Paper in progress: • Refinement and evaluation of a road dust suspension model for

predicting the concentrations of PM10 in street canyon in Helsinki.

• Kauhaniemi, Kukkonen, Härkönen, Nikmo, Kangas, Omstedt, Ketzel, Kousa, Haakana, and Karppinen

• No measured suspension emissions available

• Evaluated against observed PM10 concentrations

• PM10 concentration computed by a street canyon model (OSPM)

• Study period: 8.1.-2.5.2004

• Study site: Runeberg Street

KaisaniemiRuneberg Street

Urban background measurement station

Meteorological stationAir quality measurement station

Wind mast

Measurement sites

Sensitivity analysis

Influence of precipitation studied with: Influence of precipitation studied with: •Kaisaniemi precipitation data (0-3.8 mm/h)•No precipitation•Maximum precipitation of Kaisaniemi data (3.8 mm/h)

13

.1

1.2

3.2

5.2

15

.21

6.2

17

.22

0.2

21

.22

5.2

26

.22

7.2

1.3

2.3 9.3

12

.31

4.3

15

.3

23

.32

4.3

25

.32

6.3

27

.31

.42

.43

.4

0

100

200

300

400

500

600

700

800

900

1000

1.1 6.1 11.1 16.1 21.1 26.1 31.1 5.2 11.2 16.2 21.2 26.2 2.3 7.3 12.3 17.3 23.3 28.3 2.4 7.4 12.4 17.4 22.4 27.4

Su

sp

en

sio

n e

mis

sio

n facto

r (µ

g/v

eh

/m)

Date

SF (precipitation accounted)SF (no precipitation)SF (max precipitation)20 sanding says11 sanding days26 anding says

• SF (Kaisaniemi data) is occasionally higher than SF (no precipitation) max 48%.

Sensitivity analysis

Influence of sanding studied with: Influence of sanding studied with: •20 sanding days•11 sanding days

If Kaisaniemi precipitation data or no precipitation is used:• SF (20 sanding days) max about 15 % higher than SF (11 sanding days)If maximum precipitation data is used:• SF calculated with 20 or 11 sanding days have no difference.

13

.1

1.2

3.2

5.2

15

.21

7.2

20

.22

1.2

25

.22

6.2

27

.21

.32

.3

14

.31

5.3

23

.32

4.3

25

.32

6.3

27

.3

0

100

200

300

400

500

600

700

800

900

1000

1.1 6.1 11.1 16.1 21.1 26.1 31.1 5.2 11.2 16.2 21.2 26.2 2.3 7.3 12.3 17.3 23.3 28.3 2.4 7.4 12.4 17.4 22.4 27.4

Su

sp

en

sio

n e

mis

sio

n fa

cto

r (µ

g/v

eh

/m)

Date

1) SF (Kaisaniemi precipitation, 20 sanding days)

2) SF (Kaisaniemi precipitation, 11 sanding days)

3) SF (no precipitation, 20 sanding days)

4) SF (no precipitation, 11 sanding days)

5) SF (max precipitation, 20 or 11 sanding days)

20 sanding days

11 sanding days

FMI vs. SMHI suspension emission factors

Normalised sand dust layer (ls)

IA = 0.94

SF (FMI) is max 67% lower than SF (SMHI)

Suspension emission factor (SF)

SF (SMHI) is systematically higher than SF (FMI) because:• LSincrese is greater (SMHI: 0.048, FMI: 0.029)• LS is increased more often (SMHI: 885 times, FMI: 20 times)• LS is increased on different days and hours (e.g. SMHI: 2 Feb at 0, FMI: 1 Feb

at 23) reduction factors may influence differently on dust layer.

Daily PM10 in 8.1-2.5.2004

0

20

40

60

80

100

120

8.1. 15.1. 22.1. 29.1. 5.2. 12.2. 19.2. 26.2. 4.3. 11.3. 18.3. 25.3. 1.4. 8.4. 15.4. 22.4. 29.4.Date

Co

nc

en

tra

tio

n (

µg

/m3 ) predicted (Runeberg Street)

observed (Runeberg Street)

background (Kaisaniemi)

Cleaning & dust binding

Under-prediction: possible because•pedestrian ways cleaned after car lines,•traffic volume under-estimated?•No on-site meteorological data suspension emission factors under-estimated?

Over-prediction: due to the snowing/raining. •No on-site meteorological data suspension emission factors over-estimated?•Precipitation too light to be taken into account in the suspension model.

Under-prediction due to the cleaning of road surfaces.

•Can rise dust into the air in short time periods.•Not taken into account in the suspension model.

IA = 0.87FB = 0.03F2 = 94%

pre

dic

ted

(µ

g/m

3)

observed (µg/m3)

Daily PM10 concentrations