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| Titel |
Silicon chemistry in the mesosphere and lower thermosphere |
| VerfasserIn |
John Plane, Juan Carlos Gómez-Martín, Wuhu Feng, Diego Janches |
| 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 |
250125156
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| Publikation (Nr.) |
 EGU/EGU2016-4695.pdf |
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| Zusammenfassung |
| Silicon is one of the most abundant elements in cosmic dust, and meteoric ablation injects a
significant amount of Si into the atmosphere above 80 km. In this study, a new model for
silicon chemistry in the mesosphere/lower thermosphere is described, based on recent
laboratory kinetic studies of Si, SiO, SiO2 and Si+. Electronic structure calculations and
statistical rate theory are used to show that the likely fate of SiO2 is a 2-step hydration to
silicylic acid (Si(OH)4), which then polymerizes with metal oxides and hydroxides to
form meteoric smoke particles. This chemistry is then incorporated into a whole
atmosphere chemistry-climate model. The vertical profiles of Si+ and the Si+/Fe+
ratio are shown to be in good agreement with rocket-borne mass spectrometric
measurements between 90 and 110 km. Si+ has consistently been observed to be the major
meteoric ion around 110 km; this implies that the relative injection rate of Si from
meteoric ablation, compared to metals such as Fe and Mg, is significantly larger
than expected based on their relative chondritic abundances. Finally, the global
abundances of SiO and Si(OH)4 show clear evidence of the seasonal meteoric input
function, which is much less pronounced in the case of other meteoric species. |
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