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| Titel |
Study of the unknown HONO daytime source at a European suburban site during the MEGAPOLI summer and winter field campaigns |
| VerfasserIn |
V. Michoud, A. Colomb, A. Borbon, K. Miet, M. Beekmann, M. Camredon, B. Aumont, S. Perrier, P. Zapf, G. Siour, W. Ait-Helal, C. Afif, A. Kukui, M. Furger, J. C. Dupont, M. Haeffelin, J. F. Doussin |
| 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 ; 14, no. 6 ; Nr. 14, no. 6 (2014-03-19), S.2805-2822 |
| Datensatznummer |
250118514
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| Publikation (Nr.) |
 copernicus.org/acp-14-2805-2014.pdf |
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| Zusammenfassung |
| Nitrous acid measurements were carried out during the MEGAPOLI summer and
winter field campaigns at SIRTA observatory in Paris surroundings. Highly
variable HONO levels were observed during the campaigns, ranging from 10 ppt
to 500 ppt in summer and from 10 ppt to 1.7 ppb in winter. Significant HONO
mixing ratios have also been measured during daytime hours, comprised
between some tenth of ppt and 200 ppt for the summer campaign and between
few ppt and 1 ppb for the winter campaign. Ancillary measurements, such as
NOx, O3, photolysis frequencies, meteorological parameters
(pressure, temperature, relative humidity, wind speed and wind direction),
black carbon concentration, total aerosol surface area, boundary layer
height and soil moisture, were conducted during both campaigns. In addition,
for the summer period, OH radical measurements were made with a CIMS
(Chemical Ionisation Mass Spectrometer). This large dataset has been used to
investigate the HONO budget in a suburban environment. To do so,
calculations of HONO concentrations using PhotoStationary State (PSS)
approach have been performed, for daytime hours. The comparison of these
calculations with measured HONO concentrations revealed an underestimation
of the calculations making evident a missing source term for both campaigns.
This unknown HONO source exhibits a bell-shaped like average diurnal profile
with a maximum around noon of approximately 0.7 ppb h−1 and 0.25 ppb h−1,
during summer and winter respectively. This source is the main
HONO source during daytime hours for both campaigns. In both cases, this
source shows a slight positive correlation with J(NO2) and the product
between J(NO2) and soil moisture. This original approach had, thus,
indicated that this missing source is photolytic and might be heterogeneous
occurring at ground surface and involving water content available on the
ground. |
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