Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice
We report the detection of a spectral signature observed at 682 cm−1 by the Cassini Composite Infrared Spectrometer (CIRS) in nadir and limb geometry observations of Titan's southern stratospheric polar region in the middle of southern fall, while stratospheric temperatures are the coldest sinc...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/364481 2023-11-12T04:26:25+01:00 Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice Vinatier, Sandrine Schmitt, Bernard Bezard, Bruno Rannou, Pascal Dauphin, Cyril de Kok, R.J. Jennings, Donald Flasar, Michael Hydrologie Landscape functioning, Geocomputation and Hydrology 2018-08 application/pdf https://dspace.library.uu.nl/handle/1874/364481 en eng 0019-1035 https://dspace.library.uu.nl/handle/1874/364481 info:eu-repo/semantics/OpenAccess Titan atmosphere Infrared observations Atmospheres structures composition Article 2018 ftunivutrecht 2023-11-01T23:17:09Z We report the detection of a spectral signature observed at 682 cm−1 by the Cassini Composite Infrared Spectrometer (CIRS) in nadir and limb geometry observations of Titan's southern stratospheric polar region in the middle of southern fall, while stratospheric temperatures are the coldest since the beginning of the Cassini mission. The 682 cm−1 signature, which is only observed below an altitude of 300-km, is at least partly attributed to the benzene (C6H6) ice ν4 C-H bending mode. While we first observed it in CIRS nadir spectra of the southern polar region in early 2013, we focus here on the study of nadir data acquired in May 2013, which have a more favorable observation geometry. We derived the C6H6 ice mass mixing ratio in 5{\deg}S latitude bins from the south pole to 65{\deg}S and infer the C6H6 cloud top altitude to be located deeper with increasing distance from the pole. We additionally analyzed limb data acquired in March 2015, which were the first limb dataset available after the May 2013 nadir observation, in order to infer a vertical profile of its mass mixing ratio in the 0.1 - 1 mbar region (250 - 170 km). We derive an upper limit of ∼1.5 μm for the equivalent radius of pure C6H6 ice particles from the shape of the observed emission band. Several other unidentified signatures are observed near 687 and 702 cm−1 and possibly 695 cm−1, which could also be due to ice spectral signatures as they are observed in the deep stratosphere at pressure levels similar to the C6H6 ice ones. We could not reproduce these signatures with pure nitrile ice (HCN, HC3N,CH3CN, C2H5CN and C2N2) spectra available in the literature except the 695 cm−1 feature that could possibly be due to C2H3CN ice. Article in Journal/Newspaper South pole Utrecht University Repository South Pole |
institution |
Open Polar |
collection |
Utrecht University Repository |
op_collection_id |
ftunivutrecht |
language |
English |
topic |
Titan atmosphere Infrared observations Atmospheres structures composition |
spellingShingle |
Titan atmosphere Infrared observations Atmospheres structures composition Vinatier, Sandrine Schmitt, Bernard Bezard, Bruno Rannou, Pascal Dauphin, Cyril de Kok, R.J. Jennings, Donald Flasar, Michael Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice |
topic_facet |
Titan atmosphere Infrared observations Atmospheres structures composition |
description |
We report the detection of a spectral signature observed at 682 cm−1 by the Cassini Composite Infrared Spectrometer (CIRS) in nadir and limb geometry observations of Titan's southern stratospheric polar region in the middle of southern fall, while stratospheric temperatures are the coldest since the beginning of the Cassini mission. The 682 cm−1 signature, which is only observed below an altitude of 300-km, is at least partly attributed to the benzene (C6H6) ice ν4 C-H bending mode. While we first observed it in CIRS nadir spectra of the southern polar region in early 2013, we focus here on the study of nadir data acquired in May 2013, which have a more favorable observation geometry. We derived the C6H6 ice mass mixing ratio in 5{\deg}S latitude bins from the south pole to 65{\deg}S and infer the C6H6 cloud top altitude to be located deeper with increasing distance from the pole. We additionally analyzed limb data acquired in March 2015, which were the first limb dataset available after the May 2013 nadir observation, in order to infer a vertical profile of its mass mixing ratio in the 0.1 - 1 mbar region (250 - 170 km). We derive an upper limit of ∼1.5 μm for the equivalent radius of pure C6H6 ice particles from the shape of the observed emission band. Several other unidentified signatures are observed near 687 and 702 cm−1 and possibly 695 cm−1, which could also be due to ice spectral signatures as they are observed in the deep stratosphere at pressure levels similar to the C6H6 ice ones. We could not reproduce these signatures with pure nitrile ice (HCN, HC3N,CH3CN, C2H5CN and C2N2) spectra available in the literature except the 695 cm−1 feature that could possibly be due to C2H3CN ice. |
author2 |
Hydrologie Landscape functioning, Geocomputation and Hydrology |
format |
Article in Journal/Newspaper |
author |
Vinatier, Sandrine Schmitt, Bernard Bezard, Bruno Rannou, Pascal Dauphin, Cyril de Kok, R.J. Jennings, Donald Flasar, Michael |
author_facet |
Vinatier, Sandrine Schmitt, Bernard Bezard, Bruno Rannou, Pascal Dauphin, Cyril de Kok, R.J. Jennings, Donald Flasar, Michael |
author_sort |
Vinatier, Sandrine |
title |
Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice |
title_short |
Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice |
title_full |
Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice |
title_fullStr |
Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice |
title_full_unstemmed |
Study of Titan’s fall southern stratospheric polar cloud composition with Cassini/CIRS: Detection of benzene ice |
title_sort |
study of titan’s fall southern stratospheric polar cloud composition with cassini/cirs: detection of benzene ice |
publishDate |
2018 |
url |
https://dspace.library.uu.nl/handle/1874/364481 |
geographic |
South Pole |
geographic_facet |
South Pole |
genre |
South pole |
genre_facet |
South pole |
op_relation |
0019-1035 https://dspace.library.uu.nl/handle/1874/364481 |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782340400621551616 |