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Application of a General Finite Line Source Model for Predicting

Hydrocarbon concentration on M50 motorway in Ireland.

Rajiv Ganguly

Brian M. Broderick

Department of Civil, Structural and Environmental Engineering

Trinity College Dublin

Overview

v  Objectives

v  General Finite Line Source Model (GFLSM)

v  Comparison of Monitored and GFLSM data (M50)

v  Comparison of GFLSM with CALINE4 (M50) v  Conclusions

Overall Research Objectives

Ø  To predict vehicular pollution by using a variety of atmospheric dispersion models.

Ø  To perform studies by applying a variety of dispersion models to different road configurations to ascertain the applicability of each model.

Overall Research Objectives

Ø  To carry out inter-comparison of modelled data obtained by using a variety of dispersion models.

Ø  To recommend suitable atmospheric dispersion models for vehicular pollution prediction in Ireland.

Ø  To compare monitored and modelled air quality data by statistical and graphical analysis.

Expression for GFLSM (Luhar and Patil)

( )( ) ( )

( ) ( )⎥⎥⎦

⎤

⎢⎢⎣

⎡

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛ +++⎟⎟

⎠

⎞

⎜⎜

⎝

⎛ −−

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛ +−+⎟

⎟⎠

⎞⎜⎜⎝

⎛ −−

+=

yy

zzz

xyperfxyperfx

HzHzuu

QC

σ

θθ

σ

θθ

σσθσπ

2cossin

2cossin

,2

exp2

expsin22 2

2

2

2

0

1

Schematic representation of GFLSM

L

x

y R

θ

Road.

Study on M50 motorway.

Schematic Diagram of Sampling Location.

Receptors

Receptors

Secondary road

-240m -120m

-25m

25m 120m

240m

N M50 Motorway Inner suburbs and city centre

Input Data

§  Traffic volume §  Meteorological Conditions (wind speed, wind direction) §  Emission factors §  Briggs Horizontal and Vertical dispersion coefficients.

Output Data.

§  Background corrected concentration estimates were obtained at the receptor locations.

§  Results for ethene are shown below as they are more relevant for traffic emissions.

Results on M50 Motorway for Ethene.

variation of monitored and modelled data over sampling period at 25m

00.51

1.52

2.5

0 5 10 15 20

sampling period

conc

entr

atio

n

monitored

CALINE4GFLSM



0

0.5

1

1.5

2

0 5 10 15 20

sampling period

conc

entr

atio

n

monitored

CALINE4GFLSM



00.10.20.30.40.5

0 5 10 15 20

sampling period

conc

entr

atio

n

monitored

CALINE4GFLSM


spatial distribution of monitored and modelled concentration from road

00.20.40.60.81

0 50 100 150 200 250

receptor distance from road

mea

n co

ncen

trat

ion

monitored

CALINE4GFLSM

Results on M50 motorway for Ethene.

scatter plot for ethene concentration at 25m (for each individual hour points)

0

0.5

1

1.5

2

0 0.5 1 1.5 2

measured concentration

pred

icte

d co

ncen

trat

ion CALINE4

GFLSMM=PM=2PM=0.5P


scatter plot of ethene concentration at 120m (for each individual hour points)

0

0.1

0.2

0.3

0.4

0.5

0 0.1 0.2 0.3 0.4 0.5

measured concentration

pred

icte

d co

ncen

trat

ion

CALINE4GFLSMM=PM=0.5PM=2P


scatter plots for predicted data at 25m (for each individual hour points)

0

0.5

1

1.5

2

0 0.5 1 1.5 2

CALINE4

GFL

SM


scatter plots for predicted data at 120m (for each individual hour points)

0

0.1

0.2

0.3

0.4

0.5

0 0.1 0.2 0.3 0.4 0.5

CALINE4

GFL

SM


§  Statistical Analysis of Monitored and Predicted data (a) At 25 meters.

Monitored CALINE GFLSM Mean 0.85 0.91 0.91 SD 0.56 0.29 0.36 R 1.00 0.16 0.23 Bias 0.00 -0.06 -0.06 FB 0.00 0.07 0.07 NMSE 0.00 0.43 0.44


§  Statistical Analysis of Monitored and Predicted data

(b) At 120 meters

Monitored CALINE GFLSM Mean 0.26 0.28 0.28 SD 0.37 0.09 0.08 R 1.00 0.24 0.39 Bias 0.00 -0.03 0.04 FB 0.00 0.09 -0.2 NMSE 0.00 1.74 2.16


§  Statistical Analysis of Monitored and Predicted data (c) At 240 meters

Monitored CALINE GFLSM

Mean 0.11 0.17 0.11 SD 0.12 0.06 0.04 R 1.00 -0.15 0.06 Bias 0.00 -0.06 0.002 FB 0.00 0.41 -0.02 NMSE 0.00 1.14 1.26

Ø  For the M50 motorway site the performance of GFLSM has been found to be quite satisfactory when compared with CALINE4, an USEPA reference model

Conclusions

Ø  Further studies are in progress to determine the applicability of GFLSM model.

Ø  An analytical model, GFLSM has been discussed and has been applied at motorway conditions.

Acknowledgement.

§  This work is a part of the Environment Transport Interface (ETI) project funded by the ERTDI Research Programme.

Thank You

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