Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 10, 4245-4256, 2017
https://doi.org/10.5194/gmd-10-4245-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Methods for assessment of models
24 Nov 2017
Source apportionment and sensitivity analysis: two methodologies with two different purposes
Alain Clappier1, Claudio A. Belis2, Denise Pernigotti2, and Philippe Thunis2 1Université de Strasbourg, Laboratoire Image Ville Environnement, Strasbourg, France
2European Commission, Joint Research Centre, Ispra, Italy
Abstract. This work reviews the existing methodologies for source apportionment and sensitivity analysis to identify key differences and stress their implicit limitations. The emphasis is laid on the differences between source impacts (sensitivity analysis) and contributions (source apportionment) obtained by using four different methodologies: brute-force top-down, brute-force bottom-up, tagged species and decoupled direct method (DDM). A simple theoretical example to compare these approaches is used highlighting differences and potential implications for policy. When the relationships between concentration and emissions are linear, impacts and contributions are equivalent concepts. In this case, source apportionment and sensitivity analysis may be used indifferently for both air quality planning purposes and quantifying source contributions.

However, this study demonstrates that when the relationship between emissions and concentrations is nonlinear, sensitivity approaches are not suitable to retrieve source contributions and source apportionment methods are not appropriate to evaluate the impact of abatement strategies. A quantification of the potential nonlinearities should therefore be the first step prior to source apportionment or planning applications, to prevent any limitations in their use. When nonlinearity is mild, these limitations may, however, be acceptable in the context of the other uncertainties inherent to complex models.

Moreover, when using sensitivity analysis for planning, it is important to note that, under nonlinear circumstances, the calculated impacts will only provide information for the exact conditions (e.g. emission reduction share) that are simulated.


Citation: Clappier, A., Belis, C. A., Pernigotti, D., and Thunis, P.: Source apportionment and sensitivity analysis: two methodologies with two different purposes, Geosci. Model Dev., 10, 4245-4256, https://doi.org/10.5194/gmd-10-4245-2017, 2017.
Publications Copernicus
Download
Short summary
This work demonstrates that when the relationship between emissions and concentrations is nonlinear, sensitivity approaches, generally used for air quality planning, are not suitable to retrieve source contributions and source apportionment methods are not appropriate to evaluate the impact of abatement strategies on air quality. A simple theoretical example is used highlighting differences and potential implications for policy.
This work demonstrates that when the relationship between emissions and concentrations is...
Share