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| Titel |
A relaxed eddy accumulation system for measuring vertical fluxes of nitrous acid |
| VerfasserIn |
X. Ren, J. E. Sanders, A. Rajendran, R. J. Weber, A. H. Goldstein, S. E. Pusede, E. C. Browne, K.-E. Min, R. C. Cohen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 10 ; Nr. 4, no. 10 (2011-10-07), S.2093-2103 |
| Datensatznummer |
250002111
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| Publikation (Nr.) |
 copernicus.org/amt-4-2093-2011.pdf |
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| Zusammenfassung |
| A relaxed eddy accumulation (REA) system combined with a nitrous acid (HONO)
analyzer was developed to measure atmospheric HONO vertical fluxes. The
system consists of three major components: (1) a fast-response sonic
anemometer measuring both vertical wind velocity and air temperature, (2) a
fast-response controlling unit separating air motions into updraft and
downdraft samplers by the sign of vertical wind velocity, and (3) a highly
sensitive HONO analyzer based on aqueous long path absorption photometry
that measures HONO concentrations in the updrafts and downdrafts. A dynamic
velocity threshold (±0.5σw, where σw is a
standard deviation of the vertical wind velocity) was used for valve
switching determined by the running means and standard deviations of the
vertical wind velocity. Using measured temperature as a tracer and the
average values from two field deployments, the flux proportionality
coefficient, β, was determined to be 0.42 ± 0.02, in good
agreement with the theoretical estimation. The REA system was deployed in
two ground-based field studies. In the California Research at the Nexus of
Air Quality and Climate Change (CalNex) study in Bakersfield, California in
summer 2010, measured HONO fluxes appeared to be upward during the day and
were close to zero at night. The upward HONO flux was highly correlated to
the product of NO2 and solar radiation. During the Biosphere Effects on
Aerosols and Photochemistry Experiment (BEARPEX 2009) at Blodgett Forest,
California in July 2009, the overall HONO fluxes were small in magnitude and
were close to zero. Causes for the different HONO fluxes in the two
different environments are briefly discussed. |
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