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| Titel |
Innovative optical spectrometers for ice core sciences and atmospheric monitoring at polar regions |
| VerfasserIn |
Roberto Grilli, Olivier Alemany, Jérôme Chappellaz, Thibault Desbois, Xavier Faïn, Samir Kassi, Erik Kerstel, Michel Legrand, Nicola Marrocco, Guillaume Méjean, Suzanne Preunkert, Daniele Romanini, Jack Triest, Irene Ventrillard |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250111946
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| Publikation (Nr.) |
 EGU/EGU2015-12097.pdf |
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| Zusammenfassung |
| In this talk recent developments accomplished from a collaboration between the Laboratoire
Interdisciplinaire de Physique (LIPhy) and the Laboratoire de Glaciologie et Géophysique de
l’Environnement (LGGE) both in Grenoble (France), are discussed, covering atmospheric
chemistry of high reactive species in polar regions and employing optical spectrometers for
both in situ and laboratory measurements of glacial archives.
In the framework of an ANR project, a transportable spectrometer based on the injection
of a broadband frequency comb laser into a high-finesse optical cavity for the detection of
IO, BrO, NO2 and H2CO has been realized.[1] The robust spectrometer provides
shot-noise limited measurements for as long as 10 minutes, reaching detection
limits of 0.04, 2, 10 and 200 ppt (2Ïă) for the four species, respectively. During the
austral summer of 2011/12 the instrument has been used for monitoring, for the first
time, NO2, IO and BrO at Dumont d’Urville Station at East of Antarctica. The
measurements highlighted a different chemistry between East and West coast, with the
halogen chemistry being promoted to the West and the OH and NOx chemistry on the
East.[2]
In the framework of a SUBGLACIOR project, an innovative drilling probe has been
realized. The instrument is capable of retrieving in situ real-time vertical profiles of CH4 and
δD of H2O trapped inside the ice sheet down to more than 3 km of depth within a single
Antarctic season. The drilling probe containing an embedded OFCEAS (optical-feedback
cavity-enhanced absorption spectroscopy) spectrometer will be extremely useful for (i)
identify potential sites for investigating the oldest ice (aiming 1.5 Myrs BP records for
resolving a major climate reorganization called the Mid-Pleistocene transition occurred
around 1 Myrs ago) and (ii) providing direct access to past temperatures and climate cycles
thanks to the vertical distribution of two key climatic signatures.[3] The spectrometer
provides detection limit of 0.2 ppbv for CH4 and a precision of 0.2oÂon the δD of H2O
within ~1 min of integration time. The spectrometer and the home-made gas sampling has
been tested during an oceanographic campaign last summer in the Mediterranean Sea,
measuring the vertical distribution of CH4 dissolved in seawater. The project is now
moving forward its final goal which consists of employing the probe for a first
test season at Concordia station during the Austral summer of 2016/17, and then
for the “oldest ice challenge” drilling season scheduled in the Austral summer of
2017/18.
Finally, preliminary results on the isotope ratio measurements of CO18O,13CO2 and
13CO18O will be presented. A novel spectrometer, based on OFCAES technique employing a
Quantum Cascade Laser around 4.4 μm wavelength, offers a precision below 0.05
oÂfor the three isotopic anomalies, for 200 ppmv of CO2 samples. The optical
device will be employed for laboratory experiments coupling it with a continuous
ice-crushing extraction system for analyzing trapped bubbles of gas in Antarctica ice
cores.
[1] R. Grilli, G. Méjean, S. Kassi, I. Ventrillard, C. Abd-Alrahman, and D. Romanini,
“Frequency Comb Based Spectrometer for in Situ and Real Time Measurements of IO, BrO,
NO2, and H2CO at pptv and ppqv Levels.,” Environ. Sci. Technol., vol. 46, no. 19, pp.
10704–10, Oct. 2012.
[2] R. Grilli, M. Legrand, A. Kukui, G. Méjean, S. Preunkert, and D. Romanini, “First
investigations of IO, BrO, and NO2 summer atmospheric levels at a coastal East Antarctic
site using mode-locked cavity enhanced absorption spectroscopy,” Geophys. Res. Lett., vol.
40, pp. 1–6, Feb. 2013.
[3] R. Grilli, N. Marrocco, T. Desbois, C. Guillerm, J. Triest, E. Kerstel, and D.
Romanini, “Invited Article: SUBGLACIOR: An optical analyzer embedded in an Antarctic
ice probe for exploring the past climate,” Rev. Sci. Instrum., vol. 85, no. 111301, pp. 1–7,
2014. |
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