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| Titel |
Technical note: Evaluation of standard ultraviolet absorption ozone monitors in a polluted urban environment |
| VerfasserIn |
E. J. Dunlea, S. C. Herndon, D. D. Nelson, R. M. Volkamer, B. K. Lamb, E. J. Allwine, M. Grutter, C. R. Ramos Villegas, C. Márquez, S. Blanco, B. Cárdenas, C. E. Kolb, L. T. Molina, M. J. Molina |
| 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 ; 6, no. 10 ; Nr. 6, no. 10 (2006-08-01), S.3163-3180 |
| Datensatznummer |
250004023
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| Publikation (Nr.) |
 copernicus.org/acp-6-3163-2006.pdf |
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| Zusammenfassung |
| The performance of the EPA Federal Equivalent Method (FEM) technique for
monitoring ambient concentrations of O3 via ultraviolet absorption (UV)
has been evaluated using data from the Mexico City Metropolitan Area
field campaign (MCMA-2003). Comparisons of UV O3 monitors with open
path Differential Optical Absorption Spectroscopy (DOAS) and open path
Fourier Transform Infrared (FTIR) spectroscopy instruments in two locations
revealed average discrepancies in the measured concentrations between +13% to
−18%. Good agreement of two separate open path DOAS measurements at one
location indicated that spatial and temporal inhomogeneities were not
substantially influencing comparisons of the point sampling and open path
instruments. The poor agreement between the UV O3 monitors and the open
path instruments was attributed to incorrect calibration factors for the UV
monitors, although interferences could not be completely ruled out. Applying
a linear correction to these calibration factors results in excellent
agreement of the UV O3 monitors with the co-located open path
measurements; regression slopes of 0.94 to 1.04 and associated R2
values of >0.89. A third UV O3 monitor suffered from large spurious
interferences, which were attributed to extinction of UV radiation within
the monitor by fine particles (<0.2 µm). The overall performance of
this particular monitor was poor owing to a combination of interferences
from a contaminated particle filter and/or ozone scrubber. Suggestions for
improved operation practices of these UV O3 monitors and
recommendations for future testing are made. |
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