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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Published in:Earth, planets, and space planets, and space, 2021-11, Vol.73 (1), p.202-202, Article 202
Main Authors: Kitamura, Naritoshi, Seki, Kanako, Keika, Kunihiro, Nishimura, Yukitoshi, Hori, Tomoaki, Hirahara, Masafumi, Lund, Eric J., Kistler, Lynn M., Strangeway, Robert J.
Format: Article
Language:English
Subjects:
3. Space science
Auroral ion outflow
Auroral precipitation
Cleft ion fountain
Earth and Environmental Science
Earth Sciences
Electron density
Electron precipitation
FAST satellite
Fluctuations
Geology
Geophysics/Geodesy
Heavy ions
Illumination
Ion conics
Ion flux
Ionosphere
Magnetospheres
Magnetospheric plasma
Outflow
Plasma temperature
Polar ionosphere
Properties
Scale height
Solar effects
Zenith
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Summary: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 
ISSN:1343-8832
1880-5981
1880-5981
DOI:10.1186/s40623-021-01532-y