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| Titel |
A new cavity ring-down instrument for airborne monitoring of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere |
| VerfasserIn |
Albert A. Ruth, Steven S. Brown, Hemanth Dinesan, William P. Dube, Marc Goulette, Gerhard Hübler, Johannes Orphal, Andreas Zahn |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129811
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| Publikation (Nr.) |
 EGU/EGU2016-9974.pdf |
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| Zusammenfassung |
| The chemistry of NO3 and N2O5 is important to the regulation of both tropospheric and
stratospheric ozone. In situ detection of NO3 and N2O5 in the upper troposphere
lower stratosphere (UTLS) represents a new scientific direction as the only previous
measurements of these species in this region of the atmosphere has been via remote
sensing techniques. Because both the sources and the sinks for NO3 and N2O5 are
potentially stratified spatially, their mixing ratios, and their influence on nitrogen
oxide and ozone transport and loss at night can show large variability as a function
of altitude. Aircraft-based measurements of heterogeneous N2O5 uptake in the
lower troposphere have uncovered a surprising degree of variability in the uptake
coefficient [1], but there are no corresponding high altitude measurements.The
UTLS is routinely sampled by the IAGOS-CARIBIC program (Civil Aircraft for
the Regular Investigation of the atmosphere Based on an Instrument Container,
www.caribic-atmospheric.com), a European infrastructural program with the aim of studying
the chemistry and transport across this part of the atmosphere. An airfreight container with
15 different automated instruments from 8 European research partners is utilized
on board a commercial Lufthansa airbus 340-600 to monitor ~ 100 atmospheric
species (trace gases and aerosol parameters) in the UTLS. The instrumentation in the
CARIBIC container is now to be supplemented by a new cavity ring-down device for
monitoring nitrogen oxides, jointly developed by researchers from Cork (Ireland),
Boulder (USA) and Karlsruhe (Germany). The compact and light-weight instrument is
designed to monitor not only NO3 and N2O5, but also NO2 and O3. The detection
is based on 4 high-finesse optical cavities (cavity length ~ 44 cm). Two cavities
are operated at 662 nm (maximum absorption of NO3), the other two at 405 nm
(maximum absorption of NO2). The inlet to one of the (662)-cavities is heated
in order to thermally decompose N2O5 entirely to provide the sum of NO3 and
N2O5, with N2O5 provided by difference to a direct NO3 measurement in a separate,
unheated channel. One of the (405)-cavities is flushed continuously with NO in
order to measure O3 concentrations via quantitative conversion to NO2. The air
sampled underneath the cargo bay of the aircraft is distributed inside the instrument
through a dedicated inlet system distributing the flow over all four cavities. Flow
control, data collection, analysis, and zeroing procedures are fully automated and
controlled by dedicated electronics and software within the device. On the poster the
new instrument, its design and application within the CARIBIC program, will be
outlined.
[1] S.S. Brown, T.B. Ryerson, A.G. Wollny, C.A. Brock, R. Peltier, A.P. Sullivan, R.J.
Weber, J.S. Holloway, W.P. Dubé, M. Trainer, J.F. Meagher, F.C. Fehsenfeld, A. R.
Ravishankara, Variability in nocturnal nitrogen oxide processing and its role in regional air
quality, Science, 311 (2006) 67-70. |
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