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| Titel |
Path-integral method for the source apportionment of photochemical pollutants |
| VerfasserIn |
A. M. Dunker |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 6 ; Nr. 8, no. 6 (2015-06-12), S.1763-1773 |
| Datensatznummer |
250116407
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| Publikation (Nr.) |
 copernicus.org/gmd-8-1763-2015.pdf |
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| Zusammenfassung |
| A new, path-integral method is presented for apportioning the concentrations
of pollutants predicted by a photochemical model to emissions from different
sources. A novel feature of the method is that it can apportion the
difference in a species concentration between two simulations. For example,
the anthropogenic ozone increment, which is the difference between a
simulation with all emissions present and another simulation with only the
background (e.g., biogenic) emissions included, can be allocated to the
anthropogenic emission sources. The method is based on an existing, exact
mathematical equation. This equation is applied to relate the concentration
difference between simulations to line or path integrals of first-order
sensitivity coefficients. The sensitivities describe the effects of changing
the emissions and are accurately calculated by the decoupled direct method.
The path represents a continuous variation of emissions between the two
simulations, and each path can be viewed as a separate emission-control
strategy. The method does not require auxiliary assumptions, e.g., whether
ozone formation is limited by the availability of volatile organic compounds
(VOCs) or nitrogen oxides (NOx), and can be used for all the species
predicted by the model. A simplified configuration of the Comprehensive Air
Quality Model with Extensions (CAMx) is used to evaluate the accuracy of
different numerical integration procedures and the dependence of the source
contributions on the path. A Gauss–Legendre formula using three or
four points along the path gives good accuracy for apportioning the
anthropogenic increments of ozone, nitrogen dioxide, formaldehyde, and nitric
acid. Source contributions to these increments were obtained for paths
representing proportional control of all anthropogenic emissions together,
control of NOx emissions before VOC emissions, and control of VOC
emissions before NOx emissions. There are similarities in the source
contributions from the three paths but also differences due to the different
chemical regimes resulting from the emission-control strategies. |
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