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| Titel |
Development of a fast, urban chemistry metamodel for inclusion in global models |
| VerfasserIn |
J. B. Cohen, R. G. Prinn |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 15 ; Nr. 11, no. 15 (2011-08-01), S.7629-7656 |
| Datensatznummer |
250009966
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| Publikation (Nr.) |
 copernicus.org/acp-11-7629-2011.pdf |
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| Zusammenfassung |
| A reduced form metamodel has been produced to simulate the effects of
physical, chemical, and meteorological processing of highly reactive trace
species in urban areas, which is capable of efficiently simulating the urban
concentration, surface deposition, and net export flux of these species. A
polynomial chaos expansion and the probabilistic collocation method have been
used to develop the metamodel, and its coefficients, so that it is applicable
under a broad range of present-day and future conditions. The inputs upon
which this metamodel have been formed are based on a combination of physical
properties (average temperature, diurnal temperature range, date, and
latitude), anthropogenic properties (patterns and amounts of emissions), and
the nature of the surrounding environment (background concentrations of
species). The metamodel development involved using probability distribution
functions (PDFs) of the inputs to run a detailed parent chemical and physical
model, the Comprehensive Air Quality Model with Extensions (CAMx), thousands
of times. Outputs from these runs were used in turn to both determine the
coefficients of and test the precision of the metamodel, as compared with the
detailed parent model. It was determined that the deviations between the
metamodel and the parent mode for many important species (O3, CO, NOx,
and black carbon (BC)) were found to have a weighted RMS error less than
10 % in all cases, with many of the specific cases having a weighted RMS
error less than 1 %. Some of the other important species (VOCs, PAN, OC,
and sulfate aerosol) usually have their weighted RMS error less than 10 %
as well, except for a small number of cases. In these cases, the complexity
and non-linearity of the physical, chemical, and meteorological processing is
too large for the third order metamodel to give an accurate fit. Finally,
sensitivity tests have been performed, to observe the response of the 16
metamodels (4 different meteorologies and 4 different urban types) to a broad
set of potential inputs. These results were compared with observations of
ozone, CO, formaldehyde, BC, and PM10 from a few well observed urban
areas, and in most of the cases, the output distributions were found to be
within ranges of the observations. Overall, a set of efficient and robust
metamodels have been generated which are capable of simulating the effects of
various physical, chemical, and meteorological processing, and capable of
determining the urban concentrations, mole fractions, and fluxes of species,
important to human health and the global climate. |
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