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On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles

The ionosphere is one of the important sources for magnetospheric plasma, particularly for heavy ions with low charge states. We investigate the effect of solar illumination on the number flux of ion outflow using data obtained by the Fast Auroral SnapshoT (FAST) satellite at 3000–4150 km altitude f...

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Autores principales: Kitamura, Naritoshi, Seki, Kanako, Keika, Kunihiro, Nishimura, Yukitoshi, Hori, Tomoaki, Hirahara, Masafumi, Lund, Eric J., Kistler, Lynn M., Strangeway, Robert J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Berlin Heidelberg 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8572202/
https://www.ncbi.nlm.nih.gov/pubmed/34790028
http://dx.doi.org/10.1186/s40623-021-01532-y
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author Kitamura, Naritoshi
Seki, Kanako
Keika, Kunihiro
Nishimura, Yukitoshi
Hori, Tomoaki
Hirahara, Masafumi
Lund, Eric J.
Kistler, Lynn M.
Strangeway, Robert J.
author_facet Kitamura, Naritoshi
Seki, Kanako
Keika, Kunihiro
Nishimura, Yukitoshi
Hori, Tomoaki
Hirahara, Masafumi
Lund, Eric J.
Kistler, Lynn M.
Strangeway, Robert J.
author_sort Kitamura, Naritoshi
collection PubMed
description The ionosphere is one of the important sources for magnetospheric plasma, particularly for heavy ions with low charge states. We investigate the effect of solar illumination on the number flux of ion outflow using data obtained by the Fast Auroral SnapshoT (FAST) satellite at 3000–4150 km altitude from 7 January 1998 to 5 February 1999. We derive empirical formulas between energy inputs and outflowing ion number fluxes for various solar zenith angle ranges. We found that the outflowing ion number flux under sunlit conditions increases more steeply with increasing electron density in the loss cone or with increasing precipitating electron density (> 50 eV), compared to the ion flux under dark conditions. Under ionospheric dark conditions, weak electron precipitation can drive ion outflow with small averaged fluxes (~ 10(7) cm(−2) s(−1)). The slopes of relations between the Poynting fluxes and outflowing ion number fluxes show no clear dependence on the solar zenith angle. Intense ion outflow events (> 10(8) cm(−2) s(−1)) occur mostly under sunlit conditions (solar zenith angle < 90°). Thus, it is presumably difficult to drive intense ion outflows under dark conditions, because of a lack of the solar illumination (low ionospheric density and/or small scale height owing to low plasma temperature). GRAPHICAL ABSTRACT: [Image: see text]
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spelling pubmed-85722022021-11-15 On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles Kitamura, Naritoshi Seki, Kanako Keika, Kunihiro Nishimura, Yukitoshi Hori, Tomoaki Hirahara, Masafumi Lund, Eric J. Kistler, Lynn M. Strangeway, Robert J. Earth Planets Space Full Paper The ionosphere is one of the important sources for magnetospheric plasma, particularly for heavy ions with low charge states. We investigate the effect of solar illumination on the number flux of ion outflow using data obtained by the Fast Auroral SnapshoT (FAST) satellite at 3000–4150 km altitude from 7 January 1998 to 5 February 1999. We derive empirical formulas between energy inputs and outflowing ion number fluxes for various solar zenith angle ranges. We found that the outflowing ion number flux under sunlit conditions increases more steeply with increasing electron density in the loss cone or with increasing precipitating electron density (> 50 eV), compared to the ion flux under dark conditions. Under ionospheric dark conditions, weak electron precipitation can drive ion outflow with small averaged fluxes (~ 10(7) cm(−2) s(−1)). The slopes of relations between the Poynting fluxes and outflowing ion number fluxes show no clear dependence on the solar zenith angle. Intense ion outflow events (> 10(8) cm(−2) s(−1)) occur mostly under sunlit conditions (solar zenith angle < 90°). Thus, it is presumably difficult to drive intense ion outflows under dark conditions, because of a lack of the solar illumination (low ionospheric density and/or small scale height owing to low plasma temperature). GRAPHICAL ABSTRACT: [Image: see text] Springer Berlin Heidelberg 2021-11-06 2021 /pmc/articles/PMC8572202/ /pubmed/34790028 http://dx.doi.org/10.1186/s40623-021-01532-y Text en © The Author(s) 2021 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Full Paper
Kitamura, Naritoshi
Seki, Kanako
Keika, Kunihiro
Nishimura, Yukitoshi
Hori, Tomoaki
Hirahara, Masafumi
Lund, Eric J.
Kistler, Lynn M.
Strangeway, Robert J.
On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles
title On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles
title_full On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles
title_fullStr On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles
title_full_unstemmed On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles
title_short On the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles
title_sort on the relationship between energy input to the ionosphere and the ion outflow flux under different solar zenith angles
topic Full Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8572202/
https://www.ncbi.nlm.nih.gov/pubmed/34790028
http://dx.doi.org/10.1186/s40623-021-01532-y
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