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| Titel |
Real time, ambient air laser monitor and a novel preconcentrator for CO isotopologues |
| VerfasserIn |
Joanne Shorter, David Nelson, Mark Zahniser, Yenny Gonzalez Ramos, William Olszewski, Shuhei Ono |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250146917
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| Publikation (Nr.) |
 EGU/EGU2017-10986.pdf |
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| Zusammenfassung |
| As a key reactive species in oxidative pathways in the atmosphere, carbon monoxide (CO)
has an important role in global atmospheric chemistry. Carbon monoxide has a relatively
short lifetime ( 2 months) in the atmosphere and a number of sources, leading to spatial and
temporal variations in CO concentration. Also, the reaction of OH with CO is the major sink
for both OH and CO, thus the CO reaction with OH is crucial in determining the oxidative
capacity of the atmosphere. Changes in CO levels therefore have a significant impact on
other atmospheric gases, making it critical to better understand its sources and
sinks.
Current estimates of the sources and sinks of CO can be improved by inclusion of
high-frequency, high-precision global measurements of the 13 C/12 C and 18 O/16 O
isotopic ratios of atmospheric carbon monoxide, since the various sources and the OH sink
have different isotopic signatures. A continuous monitor of CO isotopologue ratios will
provide powerful constraints on the various sources and the atmospheric sink in both the short
and long term.
We present a new field deployable dual laser isotope monitor based on Tunable Infrared
Laser Direct Absorption Spectroscopy (TILDAS) for the simultaneous, sensitive, real time
measurement of isotopologues of carbon monoxide. Excellent precisions of 0.5 per mil for
δ13 CO and 3.0 per mil for δC18 O have been achieved with a few minutes averaging in
ambient measurements without preconcentration. To achieve higher precision, we have
developed a novel preconcentration method for separating CO from air without isotopic
fractionation. This also enabled meaningful measurements of C17 O in ambient air
samples. This automated system was integrated with the dual laser instrument. The
integrated instrument measured δ13 CO, δC17 O and δC18 O with a measurement
interval of 20 minutes. Variability of the isotopic ratios in ambient air was observed
over several days in preliminary experiments sampling rooftop air at Aerodyne
Research. |
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