Download - PM mapping in Scotland, 2007
PM mapping in Scotland, 2007
Andrew Kent
What are we presenting today?
1) Context to the work
2) Modelling process
3) Model results
4) Future work possibilities
Background
2004• Modelled concentrations for multiple pollutants for Scotland• Scotland met data (RAF Leuchars) and Scotland calibration used• Model performance no improvement on UK model• Too few sites for robust calibration and verification
2005• Remodelling undertaken in hope that more sites would help• Concluded that still more sites desireable
2006• No new modelling undertaken but assessed Scottish monitoring against UK
model output• Performance good
What did we do this year?
Modelled PM only
Take advantage of new Scottish monitoring campaign – genuine gravimetric PM for direct comparison with legislation
Outputs• PM10 and PM2.5 1x1 km background map• Modelled concentrations for major road links
Checked calibration performance
Assessed outputs against objectives relevant to Scottish Government
Scottish monitoring
Scottish Government funded expansion of monitoring campaign in 2007
Used Partisol analysers for daily gravimetric concentration
PM10
•10 sites
PM2.5
•8 sites
Used to calibrate model
Modelling process
Generalised description presented here• Full details in annual report on UK AQ Archive:http://www.airquality.co.uk/archive/reports/cat09/0807231621_dd12006mapsrep_v2.pdf
Particulate matter• Complex pollutant• Poorly understood• Many components, each with a degree of uncertainty!
Contributions to the annual mean model• Point sources – big and small point sources• Area sources – the largest contribution• Long-range transport primary – TRACK model output• Sea salt – the only ‘natural’ component in the model• SOA – output from HARM model• SIA – nitrate, sulphate, ammonium
Point sources
Big points Small points
Area sources
Dispersed emissions calibrated against monitoring data
1x1km sector specific emission grids
Emission footprint - Dispersion model output
Invert matrix for dispersion kernel
Dispersed using a kernel approach
Area source calibration
PM10 calibration PM2.5 calibration
y = 2 . 2 8 3 8 x
R 2 = 0 . 1 0 6 2
- 4
- 2
0
2
4
6
8
1 0
- 0 . 5 0 0 . 5 1 1 . 5 2 2 . 5 3
u n c a l i b r a t e d a r e a s o u r c e c o n t r i b u t i o n t o a n n u a l m e a n P M 1 0 ( µ g m - 3 , g r a v i m e t r i c )
Meas
ured
PM
10 - p
oint s
ourc
es - s
econ
dary
comp
onen
ts - lo
ng ra
nge
trans
port
prim
ary -
sea s
alt co
mpon
ent (
µg m
-3, g
ravim
etric)
A l l s i t e s
L in e a r ( A l l s i t e s )
y = 3 . 7 6 1 4 x
R 2 = 0 . 6 7 0 8
- 1
0
1
2
3
4
5
6
0 0 .3 0 .6 0 .9 1 .2 1 .5 1 .8
u n c a l i b r a t e d a r e a s o u r c e c o n t r i b u t i o n t o a n n u a l m e a n P M 2 .5 ( µ g m - 3 , g r a v i m e t r i c )
Meas
ured
PM
2.5
- poin
t sou
rces
- sec
onda
ry co
mpon
ents
- long
rang
e
trans
port
prim
ary -
sea s
alt co
mpon
ent (
µg m
-3, g
ravim
etric)
A l l s i t e s
L in e a r ( A l l s i t e s )
Slope of about 6!
VCM corrected TEOM data
Area type kernels
Formerly used 2 dispersion kernels
• Road traffic kernel• Non-road traffic kernel
Multiple calibrations for different land cover
• Large conurbations• Elsewhere
Now use• multiple kernels for different area
types• single calibration• Better describe dispersion over
different terrain• Less reliance on empirical
relationship
Additional contributions
Long range transport primary • TRACK model• Lagrangian statistical model• 10x10km grid
Secondary organic aerosol• HARM/ELMO model (Lancaster University)• Lagrangian model – changing compositions of air parcels en route to designated receptor
sites
Secondary inorganic aerosol• 28 rural sites measuring sulphate, nitrate and ammonium• Interpolating using Krigging on a 5x5km grid• Split between fine and coarse fractions
Fe and Ca rich dusts• Emission not included in NAEI so formerly part of residual in model• Distribution based on population and vehicle km travelled
Sea salt• Same method as SIA, using chloride measurements on a 5x5km grid• Split between fine (27%) and coarse (73%) – from Harrison & Yin (2006), APEG (1999)
The background map
Addition of …
•Big point sources
•Small point sources
•Calibrated area sources
•Sea salt
•Long range transport primary
•SOA
•Secondary inorganic aerosol
•Fe and Ca rich dusts
Roadside model
Uses scaled emissions from NAEI attributed to each major urban road link in UK
Roadside increment derived from roadside monitoring sites• measured roadside concentration – modelled background concentration
Calibration using roadside increment against traffic-flow adjusted emissions for each road link
Roadside model and calibration
PM10 calibration PM2.5 calibration
y = 0 .0 0 0 0 0 6 6 7 x
0 .0
1 .0
2 .0
3 .0
4 .0
5 .0
6 .0
7 .0
0 1 0 0 0 0 0 2 0 0 0 0 0 3 0 0 0 0 0 4 0 0 0 0 0 5 0 0 0 0 0 6 0 0 0 0 0 7 0 0 0 0 0 8 0 0 0 0 0
R o a d l in k g r a v im e t r ic P M 1 0 e m is s io n s ( g /k m /y e a r ) a d ju s t e d f o r t r a f f ic f lo w
PM10
road
side i
ncre
men
t (ug
m-3
, gra
vimet
ric)
y = 0 . 0 0 0 0 0 8 2 7 x
0 . 0
0 . 5
1 . 0
1 . 5
2 . 0
2 . 5
3 . 0
3 . 5
4 . 0
0 1 0 0 0 0 0 2 0 0 0 0 0 3 0 0 0 0 0 4 0 0 0 0 0 5 0 0 0 0 0 6 0 0 0 0 0
R o a d l i n k g r a v i m e t r i c P M 2 . 5 e m i s s i o n s ( g / k m / y e a r ) a d j u s t e d f o r t r a f f i c f l o w
PM2.5
road
side i
ncre
ment
(ug
m-3
, gra
vimet
ric)
Calibration checking – background maps
PM2.5 backgroundPM10 background
0
2
4
6
8
1 0
1 2
1 4
1 6
1 8
2 0
0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0
M e a s u r e d P M 1 0 ( µ g m - 3 , g r a v i m e t r i c )
Mode
lled
PM10
(µg
m-3
, gra
vimet
ric)
S c o t la n d - s p e c i f i c m o d e lU K m o d e ly = x y = x + 5 0 %y = x - 5 0 %
0
2
4
6
8
1 0
1 2
0 2 4 6 8 1 0 1 2
M e a s u r e d P M 2 . 5 ( µ g m - 3 , g r a v i m e t r i c )
Mod
elle
d PM
2.5
(µg
m-3
, gra
vim
etric
)
S c o t la n d - s p e c i f ic m o d e lU K m o d e ly = x y = x - 5 0 %y = x + 5 0 %
Calibration checking – road links
PM2.5 roadsidePM10 roadside
0
2
4
6
8
1 0
1 2
1 4
1 6
1 8
2 0
0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0
M e a s u r e d P M 1 0 ( µ g m - 3 , g r a v i m e t r i c )
Mode
lled
PM10
(µg m
-3, g
ravim
etric
)
S c o t la n d - s p e c i f i c m o d e lU K m o d e ly = x y = x - 5 0 %y = x + 5 0 %
0
1
2
3
4
5
6
7
8
9
1 0
0 1 2 3 4 5 6 7 8 9 1 0
M e a s u r e d P M 2 . 5 ( µ g m - 3 , g r a v i m e t r i c )
Mode
lled
PM2.5
(µg
m-3
, gra
vimet
ric)
S c o t la n d - s p e c i f ic m o d e lU K m o d e ly = x y = x - 5 0 %y = x + 5 0 %
Exceedences Assessment
Model outputs interrogated to calculate exceedence statistics for• area and population (from background model)• road links and road length (from roadside model)
Assessed model results against appropriate values
Pollutant Metric Objective Applies
PM10 Annual mean 18 µg m-3 Scotland only
PM10 Annual mean * 22 µg m-3 Scotland only
PM10 Annual mean * 31.5 µg m-3 UK
PM2.5 Annual mean 12 µg m-3 Scotland only
PM2.5 Annual mean 25 µg m-3 UK
Exceedences PM10
No background exceedences
Roadside exceedences• Scotland annual objective – exceeds over 4 zones• Scotland daily mean objective – exceeds over 2 zones• UK daily mean objective – no exceedences
No
. ro
ad
s
Ro
ad
len
gth
(k
m)
No
. ro
ad
s
Ro
ad
len
gth
(k
m)
No
. ro
ad
s
Ro
ad
len
gth
(k
m)
No
. ro
ad
s
Ro
ad
len
gth
(k
m)
Glasgow Urban Area 209 306.5 41 52.7 3 8.1 0 0Edinburgh Urban Area 61 103.2 7 11.1 0 0 0 0Central Scotland 237 375.9 6 6.7 2 1.2 0 0North East Scotland 138 233.5 13 12.1 0 0 0 0Highland 11 34.5 0 0 0 0 0 0Scottish Borders 38 59.9 0 0 0 0 0 0Scotland 694 1113.4 67 82.6 5 9.4 0 0
>31.5 µg m-3Zone/Agglomeration Total >18 µg m-3 >22 µg m-3
Exceedences PM2.5
No background exceedences
Roadside exceedences• Scotland 2010 objective – exceeds at 2 zones• Scotland 2020 target value – no exceedences
No
. ro
ad
s
Ro
ad
le
ng
th (
km
)
No
. ro
ad
s
Ro
ad
le
ng
th (
km
)
No
. ro
ad
s
Ro
ad
le
ng
th (
km
)
Glasgow Urban Area 209 306.5 4 10 0 0Edinburgh Urban Area 61 103.2 0 0 0 0Central Scotland 237 375.9 3 2.6 0 0North East Scotland 138 233.5 0 0 0 0Highland 11 34.5 0 0 0 0Scottish Borders 38 59.9 7 12.6 0 0
Zone/Agglomeration Total >12 µg m-3 >25 µg m-3
y = 2.1217x + 3.6054
R2 = 0.721
0
20
40
60
80
100
120
140
0 5 10 15 20 25 30 35 40 45 50 55
Measured annual mean (µg m-3)
Me
as
ure
d 9
8th
pe
rce
nti
le d
aily
me
an
(µ
g m
-3)
Scotland daily mean objective
y = 1.5553x + 0.7613
R2 = 0.9003
0
10
20
30
40
50
60
70
80
90
0 5 10 15 20 25 30 35 40 45 50
Measured annual mean (µg m-3)
Me
as
ure
d 9
0th
pe
rce
nti
le d
aily
me
an
(µ
g m
-3)
UK daily objective… for comparison
Maps - background
PM10 PM2.5
Maps - roadside
PM10 PM2.5
Background maps - difference
PM10 PM2.5
Like pollutants examined in previous years – a Scotland-specific model provides mixed results
Difference between Scotland-specific and UK models is not very large and is attributable to calibration rather than met variation
Scotland-specific model results in generally lower PM10 than UK model but are higher PM2.5. This is due to the calibration factors
derived from the monitoring data.
Largest differences between models was across urban areas – probably due to greater urban representation in UK model than in Scotland-specific model (predominantly rural calibration)
Conclusions
Will need discussion with and direction from Scottish Government
No PM mapping possible for 2008
Recommend:• Comparison of Scottish monitoring against UK model outputs – Scottish
verification
• Interrogation of UK model outputs for values relevant to Scotland – Scotland AQS values, EU limit values.
• These will provide confidence in UK outputs for Scotland
• Help identify areas of exceedence for further policy focus and action
Future work