A new auroral phenomenon, the anti-black aurora

Abstract Black auroras are small-scale features embedded in the diffuse background aurora, typically occurring post-substorm after magnetic midnight and with an eastward drift imposed. Black auroras show a significant reduction in optical brightness compared to the surrounding diffuse aurora, and ca...

Full description

Bibliographic Details
Main Authors: A. E. Nel, M. J. Kosch, D. Whiter, B. Gustavsson, T. Aslaksen
Format: Article
Language:English
Published: Nature Publishing Group 2021-01-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-021-81363-9
id doaj-cd9f586df8414c6aae82e943bf46bb51
record_format Article
spelling doaj-cd9f586df8414c6aae82e943bf46bb512021-01-24T12:31:59ZengNature Publishing GroupScientific Reports2045-23222021-01-011111910.1038/s41598-021-81363-9A new auroral phenomenon, the anti-black auroraA. E. Nel0M. J. Kosch1D. Whiter2B. Gustavsson3T. Aslaksen4Centre for Space Research, North-West UniversityThe South African National Space AgencySouthampton UniversityThe University of TromsøThe University of TromsøAbstract Black auroras are small-scale features embedded in the diffuse background aurora, typically occurring post-substorm after magnetic midnight and with an eastward drift imposed. Black auroras show a significant reduction in optical brightness compared to the surrounding diffuse aurora, and can appear as slow-moving arcs or rapidly-moving patches and arc segments. We report, for the first time, an even more elusive small-scale optical structure that has always been observed occurring paired with $$\sim$$ ∼ 10% of black aurora patches. A patch or arc segment of enhanced luminosity, distinctly brighter than the diffuse background, which we name the anti-black aurora, may appear adjacent to the black aurora. The anti-black aurora is of similar shape and size, and always moves in parallel to the drifting black aurora, although it may suddenly switch sides for no apparent reason. The paired phenomenon always drifts with the same average speed in an easterly direction. From the first dual-wavelength (427.8 nm and 844.6 nm) optical observations of the phenomenon recorded on 12 March 2016 outside Tromsø Norway, we show that the anti-black and black auroras have a higher and lower mean energy, respectively, of the precipitating electrons compared to the diffuse background.https://doi.org/10.1038/s41598-021-81363-9
collection DOAJ
language English
format Article
sources DOAJ
author A. E. Nel
M. J. Kosch
D. Whiter
B. Gustavsson
T. Aslaksen
spellingShingle A. E. Nel
M. J. Kosch
D. Whiter
B. Gustavsson
T. Aslaksen
A new auroral phenomenon, the anti-black aurora
Scientific Reports
author_facet A. E. Nel
M. J. Kosch
D. Whiter
B. Gustavsson
T. Aslaksen
author_sort A. E. Nel
title A new auroral phenomenon, the anti-black aurora
title_short A new auroral phenomenon, the anti-black aurora
title_full A new auroral phenomenon, the anti-black aurora
title_fullStr A new auroral phenomenon, the anti-black aurora
title_full_unstemmed A new auroral phenomenon, the anti-black aurora
title_sort new auroral phenomenon, the anti-black aurora
publisher Nature Publishing Group
series Scientific Reports
issn 2045-2322
publishDate 2021-01-01
description Abstract Black auroras are small-scale features embedded in the diffuse background aurora, typically occurring post-substorm after magnetic midnight and with an eastward drift imposed. Black auroras show a significant reduction in optical brightness compared to the surrounding diffuse aurora, and can appear as slow-moving arcs or rapidly-moving patches and arc segments. We report, for the first time, an even more elusive small-scale optical structure that has always been observed occurring paired with $$\sim$$ ∼ 10% of black aurora patches. A patch or arc segment of enhanced luminosity, distinctly brighter than the diffuse background, which we name the anti-black aurora, may appear adjacent to the black aurora. The anti-black aurora is of similar shape and size, and always moves in parallel to the drifting black aurora, although it may suddenly switch sides for no apparent reason. The paired phenomenon always drifts with the same average speed in an easterly direction. From the first dual-wavelength (427.8 nm and 844.6 nm) optical observations of the phenomenon recorded on 12 March 2016 outside Tromsø Norway, we show that the anti-black and black auroras have a higher and lower mean energy, respectively, of the precipitating electrons compared to the diffuse background.
url https://doi.org/10.1038/s41598-021-81363-9
work_keys_str_mv AT aenel anewauroralphenomenontheantiblackaurora
AT mjkosch anewauroralphenomenontheantiblackaurora
AT dwhiter anewauroralphenomenontheantiblackaurora
AT bgustavsson anewauroralphenomenontheantiblackaurora
AT taslaksen anewauroralphenomenontheantiblackaurora
AT aenel newauroralphenomenontheantiblackaurora
AT mjkosch newauroralphenomenontheantiblackaurora
AT dwhiter newauroralphenomenontheantiblackaurora
AT bgustavsson newauroralphenomenontheantiblackaurora
AT taslaksen newauroralphenomenontheantiblackaurora
_version_ 1724325725739155456