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Proceedings Paper

Photometric measurements of rotational temperatures in auroral forms
Author(s): Kari U. Kaila; H. J. Holma
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Paper Abstract

The distribution of the rotational states of neutral nitrogen molecules depends on the surrounding temperature. When precipitating auroral electrons penetrate into the atmosphere, they ionize and excite atoms and molecules. As a result nitrogen molecule is excited to the N2+B2(Sigma) u+ state. The lifetime of this state is so short compared with the collision frequency at auroral heights that the excited ion emits a photon before the rotational distribution is rearranged. From these emissions it is possible to estimate the rotational temperature of the emitting volume. The measurements can be made by a spectrometer or even by a filter photometer. In this paper the measurements have been made with multichannel auroral photometer by using the photon counting method. It is shown that the temperature may vary from 150 K up to 500 K. In a very intense aurora a temperature of 350 K has been obtained.

Paper Details

Date Published: 3 September 1997
PDF: 7 pages
Proc. SPIE 3237, 23rd European Meeting on Atmospheric Studies by Optical Methods, (3 September 1997); doi: 10.1117/12.284766
Show Author Affiliations
Kari U. Kaila, Univ. of Oulu (Finland)
H. J. Holma, Univ. of Oulu (Finland)

Published in SPIE Proceedings Vol. 3237:
23rd European Meeting on Atmospheric Studies by Optical Methods
Vasily N. Ivchenko, Editor(s)

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