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...

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Autores principales:	A. E. Nel, M. J. Kosch, D. Whiter, B. Gustavsson, T. Aslaksen
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/cd9f586df8414c6aae82e943bf46bb51
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spelling	oai:doaj.org-article:cd9f586df8414c6aae82e943bf46bb512021-12-02T15:23:47ZA new auroral phenomenon, the anti-black aurora10.1038/s41598-021-81363-92045-2322https://doaj.org/article/cd9f586df8414c6aae82e943bf46bb512021-01-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-81363-9https://doaj.org/toc/2045-2322Abstract 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.A. E. NelM. J. KoschD. WhiterB. GustavssonT. AslaksenNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q A. E. Nel M. J. Kosch D. Whiter B. Gustavsson T. Aslaksen A new auroral phenomenon, the anti-black aurora
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.
format	article
author	A. E. Nel M. J. Kosch D. Whiter B. Gustavsson T. Aslaksen
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 Portfolio
publishDate	2021
url	https://doaj.org/article/cd9f586df8414c6aae82e943bf46bb51
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
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A new auroral phenomenon, the anti-black aurora

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