Photometric measurements of rotational temperatures in auroral forms

Kari U. Kaila; H. J. Holma

doi:10.1117/12.284766

3 September 1997 Photometric measurements of rotational temperatures in auroral forms

Kari U. Kaila, H. J. Holma

Proceedings Volume 3237, 23rd European Meeting on Atmospheric Studies by Optical Methods; (1997) https://doi.org/10.1117/12.284766
Event: Twenty-third European Meeting on Atmospheric Studies by Optical Methods, 1996, Kiev, Ukraine

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.

Citation Download Citation

Kari U. Kaila and H. J. Holma "Photometric measurements of rotational temperatures in auroral forms", Proc. SPIE 3237, 23rd European Meeting on Atmospheric Studies by Optical Methods, (3 September 1997); https://doi.org/10.1117/12.284766

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available