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| Titel |
Eta-CMAQ air quality forecasts for O3 and related species using three different photochemical mechanisms (CB4, CB05, SAPRC-99): comparisons with measurements during the 2004 ICARTT study |
| VerfasserIn |
S. Yu, R. Mathur, G. Sarwar, D. Kang, D. Tong, G. Pouliot, J. Pleim |
| 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 ; 10, no. 6 ; Nr. 10, no. 6 (2010-03-30), S.3001-3025 |
| Datensatznummer |
250008270
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| Publikation (Nr.) |
 copernicus.org/acp-10-3001-2010.pdf |
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| Zusammenfassung |
| A critical module of air quality models is the photochemical mechanism. In
this study, the impact of the three photochemical mechanisms (CB4, CB05,
SAPRC-99) on the Eta-Community Multiscale Air Quality (CMAQ) model's
forecast performance for O3, and its related precursors has been
assessed over the eastern United States with observations obtained by
aircraft (NOAA P-3 and NASA DC-8) flights, ship and two surface networks
(AIRNow and AIRMAP) during the 2004 International Consortium for Atmospheric
Research on Transport and Transformation (ICARTT) study. The results show
that overall none of the mechanisms performs systematically better than the
others. On the other hand, at the AIRNow surface sites, CB05 has the best
performance with the normalized mean bias (NMB) of 3.9%, followed by CB4
(NMB=−5.7%) and SAPRC-99 (NMB=10.6%) for observed O3≥75 ppb,
whereas CB4 has the best performance with the least overestimation for
observed O3<75 ppb. On the basis of comparisons with aircraft P-3
measurements, there were consistent overestimations of O3, NOz,
PAN and NOy and consistent underestimations of CO, HNO3, NO2,
NO, SO2 and terpenes for all three mechanisms although the NMB values
for each species and mechanisms were different. The results of aircraft DC-8
show that CB05 predicts the H2O2 mixing ratios most closely to the
observations (NMB=10.8%), whereas CB4 and SAPRC-99 overestimated
(NMB=74.7%) and underestimated (NMB=−25.5%) H2O2 mixing
ratios significantly, respectively. For different air mass flows over the
Gulf of Maine on the basis of the ship data, the three mechanisms have
relatively better performance for O3, isoprene and SO2 for the
clean marine or continental flows but relatively better performance for CO,
NO2 and NO for southwesterly/westerly offshore flows. The results of the
O3-NOz slopes over the ocean indicate that SAPRC-99 has the
highest upper limits of the ozone production efficiency (εN) (5.8), followed by CB05 (4.5) and CB4 (4.0) although they are much
lower than that inferred from the observation (11.8), being consistent with
the fact that on average, SAPRC-99 produces the highest O3, followed by
CB05 and CB4, across all O3 mixing ratio ranges |
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