The aim of this work was to create The aim of this work was to create background and roadside maps of background and roadside maps of pollutant concentrations for Scotland pollutant concentrations for Scotland and to compare these with similar and to compare these with similar maps created for the whole of the UK.maps created for the whole of the UK.

Work undertaken within Netcen’s Work undertaken within Netcen’s Pollution Climate Mapping Team by Pollution Climate Mapping Team by Andrew Kent, supervised by John Andrew Kent, supervised by John Stedman.Stedman.

Technical queries can be directed to: Technical queries can be directed to: andrewandrew..kentkent@@aeataeat.co..co.ukuk

The technical aspects of this work will The technical aspects of this work will be available in a report soon.be available in a report soon.

IntroductionIntroduction

Why modelling and Why modelling and mapping?mapping?

A good question – given the extensive A good question – given the extensive national monitoring campaigns undertaken by national monitoring campaigns undertaken by Defra and the DAs and by LAsDefra and the DAs and by LAsMaps provide complete coverage over the Maps provide complete coverage over the modelled area, so filling in the gaps where no modelled area, so filling in the gaps where no monitoring is present.monitoring is present.Can help identify local and national scale Can help identify local and national scale ‘hotspots’ where there is no monitoring – i.e. ‘hotspots’ where there is no monitoring – i.e. selection of monitoring site location.selection of monitoring site location.At an advanced level, the maps can be used At an advanced level, the maps can be used to illustrate the impact of policy scenarios – to illustrate the impact of policy scenarios – e.g. the impact of changing emissions e.g. the impact of changing emissions legislationlegislationMaps for future years can be made based on Maps for future years can be made based on projected emissions – e.g. to show whether an projected emissions – e.g. to show whether an area is likely to meet future legislative area is likely to meet future legislative objectivesobjectives

Background map Roadside map

Examples…

The national maps – what are they used for?The national maps – what are they used for?

These cover the whole of the UK.These cover the whole of the UK.

The map outputs are provided to the The map outputs are provided to the Commission each year, together with the UK Commission each year, together with the UK monitoring data for the purposes of the Daughter monitoring data for the purposes of the Daughter Directives.Directives.

Defra and the DAs use them for policy guidance:Defra and the DAs use them for policy guidance:– Policy scenario impactsPolicy scenario impacts– Identify future compliance with AQS Objectives Identify future compliance with AQS Objectives

and Daughter Directive Limit Values.and Daughter Directive Limit Values.

Local Authorities – use background Local Authorities – use background concentrations published on the national Air concentrations published on the national Air Quality Archive as an important component of Quality Archive as an important component of the Review and Assessment process – to the Review and Assessment process – to determine air quality on a local level and decide determine air quality on a local level and decide on AQMA declaration.on AQMA declaration.

The Scottish mapping exerciseThe Scottish mapping exercise

Follows on from a similar comparison performed in Wales Follows on from a similar comparison performed in Wales between national maps and Welsh monitoring data.between national maps and Welsh monitoring data.

Useful to examine the performance of the model for specific Useful to examine the performance of the model for specific regions:regions:– Promotes confidence in use of mapped background Promotes confidence in use of mapped background

concentrations for Review and Assessment.concentrations for Review and Assessment.

– Highlights areas of model improvement for future.Highlights areas of model improvement for future.

Scotland’s different meteorological conditions, northerly Scotland’s different meteorological conditions, northerly position and more rural characteristics may be better position and more rural characteristics may be better represented in a Scotland-specific modelrepresented in a Scotland-specific model

The Scottish The Scottish modelmodel

Developed from the Developed from the national modelnational modelChanges included:Changes included:– Calibration Calibration

relationships defined relationships defined using only Scottish using only Scottish monitoring datamonitoring data

– Dispersion based on Dispersion based on Scottish Scottish meteorological data meteorological data (Edinburgh Airport, (Edinburgh Airport, 2004)2004)

A A model is only as good as what you feed it! model is only as good as what you feed it! These models are dependent on as much good These models are dependent on as much good quality quality monitoringmonitoring data as possible. data as possible.Monitoring data is used to calibrate the model Monitoring data is used to calibrate the model andand to verify the results. to verify the results.Fully ratified monitoring data from the national Fully ratified monitoring data from the national networks for 2004 was used – 11 AURN networks for 2004 was used – 11 AURN monitoring sites available (9 background and 3 monitoring sites available (9 background and 3 roadside) in 2004.roadside) in 2004.NAEI 2003 emissions data were also used in the NAEI 2003 emissions data were also used in the models.models.Meteorological data – national model uses data Meteorological data – national model uses data from Waddington; the Scotland model uses met from Waddington; the Scotland model uses met data from Edinburgh.data from Edinburgh.A data capture threshold was set for the A data capture threshold was set for the monitoring data so that sites with untrustworthy monitoring data so that sites with untrustworthy amounts of data were removed.amounts of data were removed.

About the data…About the data…

Testing the model Testing the model performance - verificationperformance - verification

Scatter plots of modelled concentrations Scatter plots of modelled concentrations vs. measured concentrationsvs. measured concentrationsShows position of modelled results Shows position of modelled results about the 1:1 line to illustrate the about the 1:1 line to illustrate the variation and any over or under variation and any over or under predictionpredictionTabulated results including averages of Tabulated results including averages of the modelled and monitored data, the modelled and monitored data, correlation coefficientscorrelation coefficientsData Quality Objectives – set a defined Data Quality Objectives – set a defined target range for modelled data in the 1target range for modelled data in the 1stst and 2and 2ndnd Daughter Directives Daughter DirectivesAdditional lines included for illustrative Additional lines included for illustrative purposes where no formal DQOs for purposes where no formal DQOs for these metricsthese metricsThe data used to calibrate was the The data used to calibrate was the same data used to verify the resultssame data used to verify the results

CO annual mean resultsCO annual mean results

CO annual mean verification CO annual mean verification 2004, mg m2004, mg m-3-3

CO annual mean map 2004, CO annual mean map 2004, mg mmg m-3-3

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Measured Annual Mean CO (mg m-3)

Mod

elle

d A

nn

ual

mea

n C

O (

mg m

-3)

Scottish Background model

Scottish roadside model

National background model

National roadside model

y = x

y = x - 50%

y = x+ 50%

NONO22 annual mean results annual mean results

NONO22 annual mean annual mean verification 2004, µg mverification 2004, µg m-3-3

NONO22 annual mean map 2004, annual mean map 2004, µg mµg m-3-3

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

Measured NO2 (ug m-3)

Mod

elle

d N

O2

(ug

m-3

)

Scottish background model

Scottish roadside model

National background model

National roadside model

y = x

y = x + 30%

y = x - 30%

PMPM1010 (TEOM) annual mean results (TEOM) annual mean results

PMPM1010 (TEOM) annual mean (TEOM) annual mean model 2004, µg mmodel 2004, µg m-3-3

PMPM1010 (TEOM) annual mean (TEOM) annual mean map 2004, µg mmap 2004, µg m-3-3

0

5

10

15

20

25

0 5 10 15 20 25

Measured PM10 (ug m-3)

Mod

elle

d P

M10

(ug

m-3

)

National background model

Scottish background model

x = y - 50%

x = y + 50%

x = y

SOSO22 15-minute results 15-minute results

SOSO22 p99.9 of 15-min mean p99.9 of 15-min mean verification 2004, µg mverification 2004, µg m-3-3

SOSO22 99.9%ile of 15-min 99.9%ile of 15-min mean map 2004, µg mmean map 2004, µg m-3-3

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300 350 400

Measured SO2 (g m-3)

Mo

del

led

SO

2 (

g m

-3)

Scotland background model

National background model

y = x

y = x + 50 %

y = x - 50 %

ConclusionsConclusions

The improvement resulting The improvement resulting from Scottish calibration from Scottish calibration may be offset by the may be offset by the additional uncertainties additional uncertainties resulting from such a small resulting from such a small number of sites used for number of sites used for calibration.calibration.

For the year 2004, there are For the year 2004, there are not really sufficient not really sufficient monitoring data available in monitoring data available in Scotland – a meaningful Scotland – a meaningful repeat of the exercise would repeat of the exercise would require a greater number of require a greater number of monitoring sites.monitoring sites.

Modelling and mapping can provide a useful source of Modelling and mapping can provide a useful source of information to supplement monitoring campaigns.information to supplement monitoring campaigns.

The national models can be tailored to Scotland, producing The national models can be tailored to Scotland, producing more accurate results for most pollutants/metrics provided that more accurate results for most pollutants/metrics provided that adequate monitoring data are available to support the model.adequate monitoring data are available to support the model.

Thank you-Thank you-any questions?any questions?