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| Titel |
A new method for continuous measurements of oceanic and atmospheric N2O, CO and CO2: performance of off-axis integrated cavity output spectroscopy (OA-ICOS) coupled to non-dispersive infrared detection (NDIR) |
| VerfasserIn |
D. L. Arévalo-Martínez, M. Beyer, M. Krumbholz, I. Piller, A. Kock, T. Steinhoff, A. Körtzinger, H. W. Bange |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 9, no. 6 ; Nr. 9, no. 6 (2013-12-11), S.1071-1087 |
| Datensatznummer |
250085282
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| Publikation (Nr.) |
 copernicus.org/os-9-1071-2013.pdf |
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| Zusammenfassung |
| A new system for continuous, highly resolved oceanic and atmospheric
measurements of N2O, CO and CO2 is described. The system is based
upon off-axis integrated cavity output spectroscopy (OA-ICOS) and a
non-dispersive infrared analyzer (NDIR), both coupled to a Weiss-type
equilibrator. Performance of the combined setup was evaluated by testing its
precision, accuracy, long-term stability, linearity and response time.
Furthermore, the setup was tested during two oceanographic campaigns in the
equatorial Atlantic Ocean in order to explore its potential for autonomous
deployment onboard voluntary observing ships (VOS). Improved equilibrator
response times for N2O (2.5 min) and CO (45 min) were achieved in
comparison to response times from similar chamber designs used by previous
studies. High stability of the OA-ICOS analyzer was demonstrated by low
optimal integration times of 2 and 4 min for N2O and CO respectively,
as well as detection limits of < 40 ppt and precision better than
0.3 ppb Hz–1/2. Results from a direct comparison of the method
presented here and well-established discrete methods for oceanic N2O
and CO2 measurements showed very good consistency. The favorable
agreement between underway atmospheric N2O, CO and CO2
measurements and monthly means at Ascension Island (7.96° S
14.4° W) further suggests a reliable operation of the underway
setup in the field. The potential of the system as an improved platform for
measurements of trace gases was explored by using continuous N2O and
CO2 data to characterize the development of the seasonal equatorial
upwelling in the Atlantic Ocean during two R/V Maria S. Merian cruises. A
similar record of high-resolution CO measurements was simultaneously
obtained, offering, for the first time, the possibility of a comprehensive view
of the distribution and emissions of these climate-relevant gases in the
area studied. The relatively simple underway N2O/CO/CO2 setup is suitable
for long-term deployment onboard research and commercial vessels
although potential sources of drift, such as cavity temperature, and further
technical improvements towards automation, still need to be addressed. |
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