An optical study of multiple NEIAL events driven by low energy electron precipitation

Optical data are compared with EISCAT radar observations of multiple Naturally Enhanced Ion-Acoustic Line (NEIAL) events in the dayside cusp. This study uses narrow field of view cameras to observe small-scale, short-lived auroral features. Using multiple-wavelength optical observations, a direct li...

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Bibliographic Details
Published in:Annales Geophysicae
Main Authors: Sullivan, J. M., Lockwood, M., Lanchester, B. S., Kontar, E. P., Ivchenko, N., Dahlgren, H., Whiter, D. K.
Format: Text
Language:English
Published: 2018
Subjects:
Langmuir
EISCAT
Online Access:https://doi.org/10.5194/angeo-26-2435-2008
https://angeo.copernicus.org/articles/26/2435/2008/
Description
Summary:Optical data are compared with EISCAT radar observations of multiple Naturally Enhanced Ion-Acoustic Line (NEIAL) events in the dayside cusp. This study uses narrow field of view cameras to observe small-scale, short-lived auroral features. Using multiple-wavelength optical observations, a direct link between NEIAL occurrences and low energy (about 100 eV) optical emissions is shown. This is consistent with the Langmuir wave decay interpretation of NEIALs being driven by streams of low-energy electrons. Modelling work connected with this study shows that, for the measured ionospheric conditions and precipitation characteristics, growth of unstable Langmuir (electron plasma) waves can occur, which decay into ion-acoustic wave modes. The link with low energy optical emissions shown here, will enable future studies of the shape, extent, lifetime, grouping and motions of NEIALs.

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