FAIRMODESub Group 2 – Contribution of Sub Group 2 – Contribution of

natural sources and source natural sources and source apportionmentapportionment

John Douros

Aristotle University of Thessaloniki, LHTEE

Modelling for source apportionment in the AQD

Source apportionment studies include assessing the contribution from local sources as well as from natural sources, neighbouring countries and the contribution from resuspended road sand and salt.

AQD: possibility to discount natural sources and long-range transport of pollution and resuspension attributable to winter sanding-salting of roads when assessing compliance against limit values.

Although not explicitly mentioned in the AQD, modelling is necessary for this purpose as monitoring of these contributions everywhere in a zone or agglomeration would be unrealistic.

SG2 of FAIRMODE (WG2)

The working sub-group (SG) on the “Contribution of natural sources and source apportionment” has been formed within the frame of WG2 on the quality assurance of models

SG2 focuses on source apportionment (SA) and the contribution of natural sources on pollutant concentrations and aims to: provide useful guidance and suggest best modelling

practices and quality assurance procedures for member countries.

promote harmonised model use for SA in the EU

SG2 – 4 Phases

Phase 1: Review of the current status of modelling practices used for source attribution and quantification of contributions by member states to identify gaps and problems.

Phase 2: Review of current practices for the evaluation of models used for SA to identify limitations and needs regarding assessment of uncertainties.

Phase 3: Model/methodology IntercomparisonPhase 4: Compile a guidance document for

model use for SA (to be finally integrated with the GD of WG1)

Expression of interest for SG2

ALASTUEY, A. KALLOS, G.

AQUILINA, N. KARPPINEN, A.

BAKLANOV, A. KRAJCOVICOVA, J.

BALDASANO, J. M. KUKKONEN, J.

BARTZIS, J. MARTIN, F.

BATCHVAROVA, E. MONKS, P.

BELIS, C. OLESEN, H.

BESSAGNET, B. PAPADOPOULOS, C.

DOGAN, E. PIROVANO, G.

DOUROS, J. QUEROL, X.

FINZI, G. SAN JOSE, R.

FRAGKOU, E. SYRAKOS, A.

FRITZEL, A. UDINA SISTACH, M.

GOODDARD, C. VAN DEN HOUT, D.

HARRISON, R. VINCENT, K.

HIRTL, M. VLCEK, O.

KAISER, A. ZANINI, G.

Modelling SA for regulation: Control & Contribution Assessments

Address relative efficacy of source/pollutant emissions reductions– Response Surface Modelling (among others)• A statistical “reduced-form” model of a complex air quality

model Address source/pollutant “contribution” to non attainment

– Sector Zero-Out Modelling• Model simulation with “zero-out” of single or all pollutants

from sector/sources of interest– Advanced SA Modelling• Allows estimation of contributions from different source

areas / categories within a single run

Receptor models are commonly used for SA

Receptor modelsReceptor models complement source models by independently identifying sources and quantifying their contributions using ambient measurements of different observables at different times and locations. SA is accomplished by solution of the mass balance equationsmass balance equations that express concentrations at several measured pollutants as a linear sum of products of pollutant abundances in source emissions and source contributions. These equations can be solved by several methods, such as PMF.

However, the solution does not guarantee physical reality, so internal and external validation measures must be evaluated. Receptor models are best used in conjunction with source models to create a “weight of evidence” for justifying emission reduction measures on different source types. (Watson and Chow; 2005)

Dispersion and Receptor Models

The dispersion model uses source emissions as inputs and calculates ambient concentrations. The receptor model uses

ambient concentrations as inputs and calculates source contributions. (Adapted from Watson, 1979.)

DISPERSIONMODEL

RECEPTOR MODEL

DISPERSION MODEL

RECEPTOR MODEL

Modelling for source apportionment

Most commonly used methods Principal Component Analysis (PCAPCA) Positive Matrix Factorization (PMFPMF) Chemical Mass Balance (CMBCMB)

Viana et al, 2008

Models for SA used by different EU countries for the time extension reports

0 5 10 15

Lagrangian

Eulerian

Trajectory

Receptor

Gaussian

CFD

Combination

No. of member countries

Mo

del

Typ

e

Conclusions so far…

SG2 Phase 1 review confirms the increased use of modelling tools for SA by member states and modellers/researchers

However, a large part of SA is carried out mostly with receptor modelling and only limited use of dispersion modelling

The analysis of the time extension reports revealed (as expected!) the lack of a uniform methodology for SA

Conclusions so far…

A standardised methodological framework and guidance would be useful, putting emphasis on issues of QA and uncertainty estimation

Still many limitations regarding:certain compounds not adequately quantified (e.g.

biogenic secondary organics, nitrate components etc.) specific anthropogenic emission sources not

sufficiently discriminated in many SA studies (e.g. shipping emissions)

the identification of biomass combustion sources

The need for QA in all model applications

Uncertainties in input data and model processes (e.g. Emissions, secondary organics, nitrate partitioning, meteo variability etc.)

Models have to be assessed to ensure that they meet certain quality objectives recommended for regulatory use. Lack of appropriate uncertainty estimates is a clear limitation when applying models for SA

Missing uncertainty data may result in restriction of the potential of the models to resolve the sources.

Future activities (1)

Phase 2 review of currently used methods for the evaluation of models used for SA applications by member states.

Provide assistance to member states regarding the use of models for NO2 SA, in view of the preparation of time extension reports for NO2. …through the NO2 guidance document and the

discussion forum now in operation in the FAIRMODE website

Future activities (2)

Update of the MDS system will take place to account for SA model applications, and thus to include SA in its structured search for appropriate models.

Continue investigating options for synergy with other projects and activities (JRC initiative, MEGAPOLI, PASODOBLE, MACC etc.) in regard to Phase 3 (intercomparison exercise).

A Guidance document on SA with emphasis on QA (Phase 4) that will be finally be integrated with the model Guidance Document.