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| Titel |
Evaluation of the United States National Air Quality Forecast Capability experimental real-time predictions in 2010 using Air Quality System ozone and NO2 measurements |
| VerfasserIn |
T. Chai, H.-C. Kim, P. Lee, D. Tong, L. Pan, Y. Tang, J. Huang, J. McQueen, M. Tsidulko, I. Stajner |
| 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 ; 6, no. 5 ; Nr. 6, no. 5 (2013-10-29), S.1831-1850 |
| Datensatznummer |
250085008
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| Publikation (Nr.) |
 copernicus.org/gmd-6-1831-2013.pdf |
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| Zusammenfassung |
| The National Air Quality Forecast Capability (NAQFC) project provides the US
with operational and experimental real-time ozone predictions using two
different versions of the three-dimensional Community Multi-scale Air Quality
(CMAQ) modeling system. Routine evaluation using near-real-time AIRNow ozone
measurements through 2011 showed better performance of the operational ozone
predictions. In this work, quality-controlled and -assured Air Quality System
(AQS) ozone and nitrogen dioxide (NO2) observations are used to
evaluate the experimental predictions in 2010. It is found that both ozone
and NO2 are overestimated over the contiguous US (CONUS), with annual
biases of +5.6 and +5.1 ppbv, respectively. The
annual root mean square errors (RMSEs) are 15.4 ppbv for ozone and
13.4 ppbv for NO2. For both species the overpredictions are
most pronounced in the summer. The locations of the AQS monitoring sites are
also utilized to stratify comparisons by the degree of urbanization.
Comparisons for six predefined US regions show the highest annual biases for
ozone predictions in Southeast (+10.5 ppbv) and for NO2 in
the Lower Middle (+8.1 ppbv) and Pacific Coast
(+7.1 ppbv) regions. The spatial distributions of the NO2
biases in August show distinctively high values in the Los Angeles, Houston, and
New Orleans areas. In addition to the standard statistics metrics, daily
maximum eight-hour ozone categorical statistics are calculated using the
current US ambient air quality standard (75 ppbv) and another lower
threshold (70 ppbv). Using the 75 ppbv standard, the hit rate
and proportion of correct over CONUS for the entire year are 0.64 and 0.96,
respectively. Summertime biases show distinctive weekly patterns for ozone
and NO2. Diurnal comparisons show that ozone overestimation is most
severe in the morning, from 07:00 to 10:00 local time. For NO2, the
morning predictions agree with the AQS observations reasonably well, but
nighttime concentrations are overpredicted by around 100%. |
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