Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 948-968 |
| Number of pages | 21 |
| Journal | Annales Geophysicae |
| Volume | 16 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - 1998 Jan 1 |
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All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Geology
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science
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Further development in theory/data closure of the photoelectron-driven polar wind and day-night transition of the outflow. / Tam, Sunny Wing-Yee; Yasseen, F.; Chang, T.
In: Annales Geophysicae, Vol. 16, No. 8, 01.01.1998, p. 948-968.Research output: Contribution to journal › Article
TY - JOUR
T1 - Further development in theory/data closure of the photoelectron-driven polar wind and day-night transition of the outflow
AU - Tam, Sunny Wing-Yee
AU - Yasseen, F.
AU - Chang, T.
PY - 1998/1/1
Y1 - 1998/1/1
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.
UR - http://www.scopus.com/inward/record.url?scp=0002967364&partnerID=8YFLogxK
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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 -