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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
Results on M50 Motorway for Ethene.
variation of monitored and modelled data over sampling period at 120m
0
0.5
1
1.5
2
0 5 10 15 20
sampling period
conc
entr
atio
n
monitored
CALINE4GFLSM
Results on M50 Motorway for Ethene.
variation of monitored and modelled data over sampling period at 240m
00.10.20.30.40.5
0 5 10 15 20
sampling period
conc
entr
atio
n
monitored
CALINE4GFLSM
Results on M50 Motorway for Ethene.
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
Results on M50 motorway for Ethene.
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
Results on M50 motorway for Ethene.
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
Results on M50 motorway for Ethene.
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
Results on M50 motorway for Ethene.
§ 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
Results on M50 motorway for Ethene.
§ 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
Results on M50 motorway for Ethene.
§ 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