TY - JOUR
T1 - Further development in theory/data closure of the photoelectron-driven polar wind and day-night transition of the outflow
AU - Tam, S. W.Y.
AU - Yasseen, F.
AU - Chang, T.
N1 - Funding Information:
Acknowledgement: The authors would like to thank J.R. Jasperse, J.D. Winningham, Andrew Yau, and Takumi Abe for many useful discussions, John Retterer for participating in the initial stage of the investigation, and Supriya Ganguli for constant collaboration. This work is supported by NSF Grant ATM-9634599, AFOSR Grants F49620-93-1-0287 and F49620-96-1-0340, NASA Grant NAG5-2255, and AF Contract F19628-91-K-0043. Portion of this work was performed at the International Space Science Institute, Bern, Switzerland. T.C. and F.Y. wish to thank Professors
PY - 1998/8
Y1 - 1998/8
N2 - Recent in situ observations have revealed novel features in the 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. 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. Here, we discuss the further development of a theory by Tam et al. that can explain most of these observed peculiar properties by properly taking into account the global, kinetic, collisional effects of the sunlit photoelectrons, on the background polar wind and the electric field. Quantitative comparisons of the calculated results with actual data will be described. In addition, transition from the daytime photoelectrondriven polar wind to the night-time polar wind will be discussed.
AB - Recent in situ observations have revealed novel features in the 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. 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. Here, we discuss the further development of a theory by Tam et al. that can explain most of these observed peculiar properties by properly taking into account the global, kinetic, collisional effects of the sunlit photoelectrons, on the background polar wind and the electric field. Quantitative comparisons of the calculated results with actual data will be described. In addition, transition from the daytime photoelectrondriven polar wind to the night-time polar wind will be discussed.
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U2 - 10.1007/s00585-998-0948-2
DO - 10.1007/s00585-998-0948-2
M3 - Article
AN - SCOPUS:0002967364
VL - 16
SP - 948
EP - 968
JO - Annales Geophysicae
JF - Annales Geophysicae
SN - 0992-7689
IS - 8
ER -