Observations of downward moving O{sup +} in the polar topside ionosphere

Journal Article · Sat Apr 01 04:00:00 EST 1995 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JA03236· OSTI ID:166216

Chandler, M O ^[1]

---

1. NASA Marshall Space Flight Center, Huntsville, AL (United States)

New investigations of the core ion motion within the high-latitude topside ionosphere and near-Earth magnetosphere, using data from the Dynamics Explorer retarding ion mass spectrometer (RIMS), reveal the existence of significant regions of downward moving O{sup +} are clearly separable in terms of either solar zenith angle or Kp but are well distinguished by the direction of the z component of the interplanetary magnetic field (IMF). On average, downflow dominates when IMF B{sub z}O. Combining cross-field convection velocities yields derived from an empirical convection electric field model with the observed parallel velocities yields a two-dimensional ion velocity field. This velocity field is consistent with a scenario which has O{sup +} of cusp/cleft and auroral zone origin convecting into the polar cap and, because of the dominance of gravitational energy over the upward kinetic energy, falling back into the ionosphere. This provides additional confirmation of the results of studies of the cleft ion fountain. Estimates of the flux of O{sup +} in the upflowing and downflowing regions for {Lambda} {ge} 60{degrees} give a total upflow of {approximately}6x10{sup 25} ions s{sup {minus}1}, respectively, for IMF B{sub z}

• OSTI ID: 166216
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A4 Vol. 100; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ALTITUDE
CONVECTION
IONOSPHERE
OXYGEN IONS
POLAR REGIONS
VELOCITY