Ionospheric evidence of thermosphere-to-stratosphere descent of polar NOx

During the northern hemisphere winter of 2003–2004 significant levels of stratospheric odd nitrogen (NOX) were observed descending from the mesosphere. Here we study subionospheric radio wave propagation data from Ny Ålesund, Svalbard, Norway to determine the origin of the mesospheric NOX. A clear c...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Clilverd, Mark A., Seppala, Annika, Rodger, Craig J., Verronen, Pekka T., Thomson, Neil R.
Format: Article in Journal/Newspaper
Language:unknown
Published: American Geophysical Union 2006
Subjects:
Atmospheric Sciences
Space Sciences
Norway
Ny-Ålesund
Svalbard
Ny Ålesund
Online Access:http://nora.nerc.ac.uk/id/eprint/923/
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2006GL026727
https://doi.org/10.1029/2006GL026727
Description
Summary:During the northern hemisphere winter of 2003–2004 significant levels of stratospheric odd nitrogen (NOX) were observed descending from the mesosphere. Here we study subionospheric radio wave propagation data from Ny Ålesund, Svalbard, Norway to determine the origin of the mesospheric NOX. A clear change in the radio wave diurnal variation is observed, starting on January 13, 2004, lasting for 37 days. The behavior is consistent with the ionization, by Lyman-α, of thermospheric NOX descending into the mesosphere from altitudes above 90 km. Estimates of the concentration of NOX required to produce the observed ionization changes are consistent with the levels of previously published stratospheric mixing ratios after the NOX has descended into the stratosphere. The radio wave data shows that no significant proton or electron precipitation events into the mesosphere occurred at this time, and the mesospheric effects of the large storms in October/November 2003 had abated by late December 2003.

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