Why Does the October Effect Not Occur at Night?

Wendt, V.; Schneider, H.; Banyś, D.; Hansen, M.; Clilverd, M.A. ORCID: https://orcid.org/0000-0002-7388-1529; Raita, T.. 2024 Why Does the October Effect Not Occur at Night? Geophysical Research Letters, 51 (7), e2023GL107445. 9, pp. https://doi.org/10.1029/2023GL107445

Before downloading, please read NORA policies.

Preview

Text (Open Access) © 2024. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Geophysical Research Letters - 2024 - Wendt - Why Does the October Effect Not Occur at Night.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (1MB) | Preview

Abstract/Summary

The October effect is known as a rapid and strong decrease in the signal amplitude of radio waves with very low frequency (VLF), reflected at the lowest edge of the ionosphere. This strong decrease can be observed only during the daytime. Although the October effect is long known, it is hardly investigated and its mechanism is still unknown. To get closer to a mechanism, we answer why the October effect does not occur during nighttime. Therefore, average characteristics of the October effect are obtained from different VLF transmitter-receiver combinations. The occurrence of the October effect is then compared with characteristics of the neutral atmosphere temperature at VLF reflection heights as it seems to act as a proxy for the unknown mechanism. The temperature shows an asymmetric seasonal behavior at daytime VLF reflection heights poleward of 50°N but not during the nighttime, resulting in the October effect.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2023GL107445
ISSN:	0094-8276
Additional Keywords:	October effect; VLF observations; dynamical cause; nighttime versus daytime; VLF reflection height
Date made live:	08 Apr 2024 11:16 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/537233

Actions (login required)

View Item

Document Downloads

More statistics for this item...