Day-night asymmetry of polar outflow due to the kinetic effects of anisotropic photoelectrons

Sunny W.Y. Tam, Fareed Yasseen, Tom Chang

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Citation (Scopus)


Recent polar wind measurements between 5000 and 9000 km altitude by the Akebono satellite indicate that both H+ and O+ ions can have remarkably higher outflow velocities in the sunlit region than on the nightside. In addition, electrons also display an asymmetric behavior: the dayside difference in energy spread, greater for upward-moving than downward-moving electrons, is absent on the nightside. We use a self-consistent hybrid model [Tam et ai, 1995b] that was developed for the polar wind outflow to address these observed day-night asymmetric features. The model takes into account the evolution of the polar wind self-consistently by properly recognizing the global, kinetic, collisional effects of the sunlit photoelectrons. By studying the effects of the presence and absence of photoelectrons on the polar outflow, we compare the daytime and night-time polar wind results, and demonstrate the asymmetries observed by the Akebono satellite.

Original languageEnglish
Title of host publicationGeospace Mass and Energy Flow
Subtitle of host publicationResults From the International Solar-Terrestrial Physics Program, 1998
EditorsJames L. Horwitz, William K. Peterson, Dennis L. Gallagher
PublisherBlackwell Publishing Ltd
Number of pages10
ISBN (Electronic)9781118664162
ISBN (Print)9780875900872
Publication statusPublished - 1998

Publication series

NameGeophysical Monograph Series
ISSN (Print)0065-8448
ISSN (Electronic)2328-8779

All Science Journal Classification (ASJC) codes

  • Geophysics


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