10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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A European-wide Intercomparison for Source Apportionment with Receptor and Chemical Transport Models
CLAUDIO BELIS, Denise Pernigotti, Guido Pirovano, FAIRMODE WG3 Community, European Commission - Joint Research Centre
Abstract Number: 79 Working Group: Source Apportionment
Abstract Assessing the performance of Source Apportionment (SA) model results is a key part of guaranteeing the quality of information on source contributions to be used in the development of pollution abatement strategies.
The performance of the source apportionment model applications was evaluated by FAIRMODE WG3, by comparing the model results for PM10 provided by 44 participants using a methodology based on performance indicators: z-scores and RMSEu, with pre-established acceptability criteria (Belis et al., 2015).
Comparing models based on completely different and independent input data, such as receptor models (RMs) and chemical transport models (CTMs), provided a unique opportunity to cross-validate them. In addition, comparing the modelled source chemical profiles, with those measured directly at the source (e.g. SPECIEUROPE, Pernigotti et al., 2016) contributed to corroborate the chemical profile of the tested model results.
One of the distinctive features of this CTMs-RMs inter-comparison is that both kinds of models were applied on the same study area so called “reference site” thereby generating an unprecedented dataset of both source oriented and receptor oriented of source contribution estimates (SCEs). Moreover, the intercomparison was also an opportunity to compare the “tagged species” and “brute force” CTM SA approaches. The former keeps track of the emission source from which every chemical component derives while the latter is based on scenario analysis.
The most used RM was EPA- PMF5. RMs showed very good performance for the overall dataset (91% of z-scores accepted) and more difficulties were observed with SCE time series (72% of RMSEu accepted). Industry was the most problematic source for RMs due to the high variability among participants.
The results obtained with CTMs were quite comparable to their ensemble reference using all models for the overall average (>92% of successful z-scores) while the comparability of the time series was more problematic (between 58% and 77% of the candidates’ RMSEu were accepted). In the CTM models a gap was observed between the sum of source contributions and the gravimetric PM10 mass likely due to PM underestimation in the base case. Interestingly, when CTM results based only on tagged species methods were used in the reference, the differences between the two CTM approaches (brute force and tagged species) were evident. In this case the percentage of candidates passing the z-score and RMSEu tests were only 50% and 86%, respectively.
CTMs showed good comparability with RMs for the overall dataset (83% of the z-scores accepted), more differences were observed when dealing with the time series of the single source categories. In this case the share of successful RMSEu fell in the range 25% - 34%.
References
Belis, C.A., Pernigotti, D., Karagulian, F., Pirovano, G., Larsen, B.R., Gerboles, M., Hopke, P.K. A new methodology to assess the performance and uncertainty of source apportionment models in intercomparison exercises (2015) Atmospheric Environment, 119, pp. 35-44.
Pernigotti, D., Belis, C.A., Spanó, L. SPECIEUROPE: The European data base for PM source profiles (2016) Atmospheric Pollution Research, 7 (2), pp. 307-314.