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| Titel |
Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere |
| VerfasserIn |
H. Volten, J. B. Bergwerff, M. Haaima, D. E. Lolkema, A. J. C. Berkhout, G. R. Hoff, C. J. M. Potma, R. J. Wichink Kruit, W. A. J. Pul, D. P. J. Swart |
| 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 ; 5, no. 2 ; Nr. 5, no. 2 (2012-02-21), S.413-427 |
| Datensatznummer |
250002467
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| Publikation (Nr.) |
 copernicus.org/amt-5-413-2012.pdf |
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| Zusammenfassung |
| We present two Differential Optical Absorption Spectroscopy (DOAS)
instruments built at RIVM: the RIVM DOAS and the miniDOAS. Both instruments
provide virtually interference-free measurements of NH3 concentrations
in the atmosphere, since they measure over an open path, without suffering
from inlet problems or interference problems by ammonium aerosols
dissociating on tubes or filters. They measure concentrations up to at least
200 μg m−3, have a fast response, low maintenance demands,
and a high up-time. The RIVM DOAS has a high accuracy of typically
0.15 μg m−3 for ammonia for 5-min averages and over a total
light path of 100 m. The miniDOAS has been developed for application in
measurement networks such as the Dutch National Air Quality Monitoring
Network (LML). Compared to the RIVM DOAS it has a similar accuracy, but is
significantly reduced in size, costs, and handling complexity. The RIVM DOAS
and miniDOAS results showed excellent agreement (R2 = 0.996) during a
field measurement campaign in Vredepeel, the Netherlands. This measurement
site is located in an agricultural area and is characterized by highly
variable, but on average high ammonia concentrations in the air. The
RIVM-DOAS and miniDOAS results were compared to the results of the AMOR
instrument, a continuous-flow wet denuder system, which is currently used in
the LML. Averaged over longer time spans of typically a day, the (mini)DOAS
and AMOR results agree reasonably well, although an offset of the AMOR values
compared to the (mini)DOAS results exists. On short time scales, the
(mini)DOAS shows a faster response and does not show the memory effects due
to inlet tubing and transport of absorption fluids encountered by the AMOR.
Due to its high accuracy, high uptime, low maintenance and its open path, the
(mini)DOAS shows a good potential for flux measurements by using two (or
more) systems in a gradient set-up and applying the aerodynamic
gradient technique. |
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