Guidance on the use of models for the European Air Quality

DirectiveActivity of WG1 FAIRMODE

Forum for air quality modelling in Europe

Bruce DenbyBruce Denby1, Emilia Georgieva6, Steinar Larssen1, Cristina Guerreiro1, Liu Li1, John Douros2, Nicolas Moussiopoulos2, Lia Fragkou2, Michael Gauss3, Helge Olesen4, Ana Isabel Miranda 5, Panagiota Dilara6, Philippe Thunis6, Sari Lappi7, Laurence Rouil8, Anke Lükewille9, Xavier Querol10, Fernando Martin11, Martijn Schaap12, Dick van den Hout12, Andrej Kobe13, Camillo Silibello14, Keith Vincent15, John Stedman15, María Gonçalves16, Guido Pirovano17, Luisa Volta18, Addo van Pul19, Alberto González Ortiz20, Peter Roberts21, Dietmar Oettl22

Presentation

• General guidance document• NO2 guidance document

• Work plan, needs and discussion

Terms of reference of FAIRMODE

• To provide a permanent European forum for AQ modellers and model users

• To produce guidance on the use of air quality models for the purposes of implementation of the AQ Directive and in preparation for its revision

• To study and set-up a system (protocols and tools) for quality assurance and continuous improvements of AQ models

• To make recommendations and promote further research in the field of AQ modelling

General guidance document

• Aimed at modellers and authorities, providing interpretation and guidance in the application of models for the AQD

• Current version (v6.1) available on FAIRMODE home page• Input from 2nd FAIRMODE plenary November 2009 • Some new examples in, some old examples out• Comments from the implementation group

• ‘Does not include direct guidance on modelling itself’ (Dick van den Hout)

CONTENT: General guidance (pp. 99)

1. Introduction

2. Summary of the 2008 AQ Directive

3. Interpretation of the AQ Directive in regard to modelling

4. Reporting and public information when using models

5. Model quality assurance and evaluation

6. Applications of models for assessment

7. Application of models for air quality planning

8. Special topics

Annexes with examples

EXAMPLES: General modelling guidance

Spatial representativeness and modelling (p. 17)• For industrial sites concentrations should be representative

of a 250 x 250 m area

• For traffic emissions the assessment should be representative for a 100 m street segment and monitoring should be carried out less than 10 m from the kerbside

• Urban background concentrations should be representative of the exposure of the general urban population (‘several square kilometres’)

EXAMPLES: General modelling guidance

Consequences of spatial representativeness when modelling traffic

• Models used for assessing near road concentrations are Gaussian based models (street canyon or open road)

• Positioning of receptors has impact on the modelled concentrations

• Model receptors should be positioned at kerbside (AQD ‘valid everywhere’) and within the breathing zone (1.5 – 4m)

• Model receptors on both sides of a road every 100 m is sufficient for roads longer than 100 m.

EXAMPLES: General modelling guidance

Interpretation of the Directive quality objective (p. 20)

• Quality objectives for modelling provided in Annex I

• Most modellers present results in terms of some interpretation of these objectives

• No standard interpretation exists

• Relative Percentile Error

• Relative Directive Error

p

pp

O

MORPE

LV

MORDE

LVLV

Uses observed concentrations at the percentile

Uses concentrations closest to the limit value

EXAMPLES: General modelling guidance

Interpretation of the Directive quality objective (p. 20)

p

pp

O

MORPE

LV

MORDE

LVLV

EXAMPLES: General modelling guidance

Interpretation of the Directive quality objective

• RDE ”reasonable” for percentiles or when O < LV but unnecessarily stringent when O > LV

• RPE ”reasonable” for annual means when O > LV but unnecessarily stringent when O < LV

Recommendations:• Review these criteria for the following Directive

p

pp

O

MORPE

LV

MORDE

LVLV

FAIRMODE general guidance work plan

• General guidance document will be updated regularly, and available from FAIRMODE website.

• Some comments received in 2010 still to be addressed (not possible to address all!)

• Current version seen as complete but improvable

• Will be published as an ETC/ACC technical paper after a final update this year.

CONTENT: NO2 modelling guidance

1. Introduction

2. Dispersion modelling

3. Chemistry modelling

4. Emission data and inventories

5. Meteorological data

6. Quality control

7. Modelling requirements for notification of postponement

CONTENT: NO2 modelling guidance

• Modelling chapters include• Description• Application• Examples• Recommendations

• Focus of the modelling is on street and urban applications

• Focus of emissions is on traffic

STATUS: NO2 modelling guidance

• First draft version available (v2.2) on FAIRMODE homepage

• Aimed at authorities, providing background information, links and recommendations on modelling methods and applications for NO2

• Presentations at the NO2 ‘postponement’ workshop in Brussels and Harmo13 conference

• Focus on the actual modelling rather than the general application of models for the AQD

Dispersion: Examples

• Gaussian models• Open roads (Caline 4, CAR-FMI, OML-Highway, …)• Street canyons (OSPM, IMMIScpb, SEP_SCAM)• Urban (URBIS, IMMISluft, ADMS-urban, …)

• Lagrangian particle models• Street level (GRAL)

• Urban (AUSTRAL, SPRAY, FLEXPART)

• Eulerian models• Obstacle resolving (Fluidyn, VADIS, MIMO, …)

• Urban (CAMx, TAPM, CMAQ, WRF-CHEM, CHIMERE, MATCH, MEMO, …)

Dispersion: Recommendations

Transport and dispersion

Gaussian models Lagrangian particle models

CFD or LES models Urban scale Eulerian models

Open roads Computationally more expensive

Computationally expensive, no obstacles

Inappropriate resolution

Street canyon Computationally moer expensive

Computationally expensive

Inappropriate resolution

Urban scale Requires homogenous meteorology

Computationally expensive

Not computationally feasible

Chemistry Non-reactive with deposition and decay

Non-reactive with deposition and decay

Possible but not operational

Full chemistry possible

State of the artConditionally applicable

Not fit for purpose

’Fitness for purpose’ of dispersion models for Directive related applications

Chemistry: NO2 dependence

• The total NOx emission

• The primary NO2 emission

• The VOC emission

• The existing chemical balance in the atmosphere

• The available ozone (and other oxidants)

• The distance from the source (time)

• The degree of turbulent mixing

Chemistry: local scale modelling

How do local scale models represent the chemistry?

•Majority use empirical functions relating NO2 to NOx (dependent on year, city, site)

•Some (~4) use photostationary approximation (only valid far from sources)

•Some (~3) use parameterised ’distance from source’ dependent solutions (more realistic)

•Some (~2) use parameterised ’limitted mixing’ dependent solutions (reflects the turbulent mixing)

Chemistry: urban scale modelling

How do urban scale models represent the chemistry?

•Empirical functions relating NO2 to NOx

•Some (~3) use photostationary approximation (only really valid when hydrocarbons are not involved)

•Some (~2) use ’reduced’ photochemical schemes (e.g. Generic Reaction Scheme)

•A number use ’complete’ photochemical schemes (based on regional scale CTMs)

Chemistry: empirical functions

Bächlin W., R. Bösinger, 2008: Untersuchungen zu Stickstoffdioxid-Konzentrationen, Los 1 Überprüfung der

Rombergformel. Ingenieurbüro Lohmeyer GmbH & Co. KG, Karlsruhe. Projekt 60976-04-01, Stand: Dezember 2008. Gutachten im Auftrag von: Landesamt für Natur, Umwelt

und Verbraucherschutz Nordrhein--Westfalen, Recklinghausen.

][][

][ ][ 2 x

x

x NOCBNO

NOANO

Chemistry: European NO2 v’s NOX

0 50 100 150 200 250 300 3500

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120

Concentration NOX (g/m3)

Co

nce

ntr

atio

n N

O 2 ( g

/m3 )

Comparison of NO2 and NO

X annual mean from Airbase (2006 - 2008)

Traffic stationsBackground stations

A=30B=42C=0.26

0 50 100 150 200 250 300 3500

20

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80

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Concentration NOX (g/m3)

Co

nce

ntr

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O 2 ( g

/m3 )

Comparison of NO2 and NO

X annual mean from Airbase (2006 - 2008)

Traffic stationsBackground stationsFit

][][

][ ][ 2 x

x

x NOCBNO

NOANO

991 traffic station data 1539 background station data

0 20 40 60 80 100 1200

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Predicted concentration NO2 (g/m3)

Ob

serv

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co

nce

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O 2 ( g

/m3 )

Observed and predicted annual mean NO2, Airbase (2006 - 2008)

+/-30%+/-30%+/-30%

Traffic stationsBackground stations

Chemistry: European NO2 v’s NOX

93% of stations within +/- 30%

Model performance for NO2

• Generally the results can be quite reasonable on the local and urban scale.

• Published validations tend to be biased towards ‘publishable’ results

• Some models will perform ‘better’ for NO2 than for NOx due to:• decreased sensitivity of NO2 with increasing NOX

• the use of measured ozone as a boundary condition• the use of empirical NOX conversions

• Results are always dependent on input data: emissions, meteorology and background.

Model results: OSPM (Copenhagen)

Berkowicz, R., Hertel, O., Larsen, S. E., Sørensen, N. N. and Nielsen, M. (1997): Modelling traffic pollution in streets. National Environmental Research Institute, Roskilde, Denmark. ISBN: 87-7772-307-4.

NOx NO2

Ingrid Sundvor, Leiv Håvard Slørdal and Scott Randall (2009) Dispersion and Exposure Calculations of PM10, NO2 and Benzene in Oslo and Trondheim for 2007. NILU: OR 9/2009

Model results: HIWAY-2 (Oslo two sites)

V. Diegmann, S. Wurzler (2009) QUALITY CONTROL IN DISPERSION MODELING: VALIDATION OF A SCREENING MODEL FOR PM10 AND NO2. Proceedings of the 12’th Harmonisation conference, Croatia

Model results: IMMISluft (N. Rhine Westphalia)

Annual mean NO2

Sokhi , R.S. et al. An integrated multi-model approach for air quality assessment: Development and evaluation of the OSCAR Air Quality Assessment System, Environmental Modelling & Software, v.23 n.3, p.268-281, March, 2008

Model results: CAR-FMI (Helsinki and London)

NOx

NO2

Helsinki London

Figure 1: NO2 model validation at background sites for 2008

Figure 2: NO2 model validation at roadside sites for 2008.

0

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0 10 20 30 40 50 60 70

Mo

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lled

NO

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g m

-3)

Measured NO2 (µg m-3)

National Network

Verification Sites

x = y

x = y + 30%

x = y - 30%

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140

0 20 40 60 80 100 120 140

Measured NO2 (µg m-3)

Mo

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(µg

m-3

)

National Network

Verification Sites

x = y

x = y + 30%

x = y - 30%

Model results: PCM - Grice et al., 2009 (UK)

Chemistry: recommendations

ChemistryEmpirical schemes

Photostationaryand ozone limitting schemes

Distance from source and mixing schemes

Reduced photochemical schemes

Full photochemical schemes

Assessment

Street level Given sufficient observations

Overestimates NO2 Difficult to apply at this scale

Urban scale Given sufficient observations

Suitable for winter or low hydrocarbons

Suitable for winter or low hydrocarbons

Regional scale Missing significant chemistry

Planning

Street level

Not sensitive to changes in ozone or NO2 emissions

Sensitivity to ozone and NO2 emissions represented

Difficult to apply at this scale

Urban scale

Not sensitive to changes in ozone or NO2 emissions

Suitable with low light or hydrocarbons

Suitable with low light or hydrocarbons

Regional scale Missing significant chemistry

State of the artConditionally applicable

Not fit for purpose’Fitness for purpose’ assessment for NO2 chemistry

• The NO2 modelling guidance is under development, 80% complete.

• NO2 guidance will also be used in a trial web based guidance scheme to be tested at the end of 2010.

• Need community involvement for contributions, review and discussion

• Example tables• Modelling experience• Development of recommendations

FAIRMODE NO2 guidance work plan

FAIRMODE NO2 guidance work plan Chapter Content (sub-chapters) Review

1. Introduction

2. Dispersion modelling RIVM

3. Chemistry modelling RIVM

4. Emission data and inventories

Borges and Lumbreras (all)Christian Nagl UBV (all)

Christian Nagl (UBV)

5. Meteorological data

6. Quality control

7. Modelling requirements for notification of post.

http://fairmode.ew.eea.europa.eu/

For information and contributions contact

Bruce Denbybde@nilu.no