Vertical Ion Flow in the Polar Ionosphere

  1. T. E. Moore,
  2. J. H. Waite Jr.,
  3. T. W. Moorehead and
  4. W. B. Hanson
  1. A. W. Yau1 and
  2. M. Lockwood2

Published Online: 18 MAR 2013

DOI: 10.1029/GM044p0229

Modeling Magnetospheric Plasma

Modeling Magnetospheric Plasma

How to Cite

Yau, A. W. and Lockwood, M. (1988) Vertical Ion Flow in the Polar Ionosphere, in Modeling Magnetospheric Plasma (eds T. E. Moore, J. H. Waite, T. W. Moorehead and W. B. Hanson), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM044p0229

Author Information

  1. 1

    Herzberg Institute of Astrophysics, National Research Council Canada, Ottawa, Canada K1A 0R6

  2. 2

    Rutherford Appleton Laboratory, Chilton, Didcot OX11 OQX UK

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1988

ISBN Information

Print ISBN: 9780875900704

Online ISBN: 9781118664414

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Keywords:

  • Space plasmas—Mathematical models;
  • Magnetosphere—Mathematical models;
  • Ionosphere—Mathematical models

Summary

Outflowing ions from the polar ionosphere fall into two categories: the classical polar wind and the suprathermal ion flows. The flows in both these categories vary a great deal with altitude. The classical polar wind is supersonic at high altitude: at ∼3 RE geocentric, the observed polar wind is H+ dominated and has a Mach number of 2.5–5.1. At 400–600 km, thermal and suprathermal upward O+ ion fluxes frequently occur at the poleward edge of the nightside auroral oval during magnetically active times. Above 500 km, ions are accelerated transverse to the local geomagnetic field. At 1400 km, transversely accelerated ions are frequently observed in winter nights but rarely appear in the summer. In the dayside cleft above ∼2000 km, ions of all species are transversely heated and upwell with significant number and heat fluxes, forming a cleft ion fountain as they convect across the polar cap. Upwelling ions are observed most (least) frequently in the summer (winter). At yet higher altitudes, energetic (>10 eV to several kiloelectron volts) upflowing H+ and O+ ions are frequently observed, their active time occurrence frequency being as high as 0.7 at auroral latitudes and 0.3 in the polar cap. Their composition, intensity, and angular characteristics vary quantitatively with solar activity, being O+ dominant and more intense near solar maximum. Their resulting ion outflow is dominated by ions below 1 keV and reaches 3.5×1026 O+ and 7×1025 H+ ions s−1 at magnetically active times (Kp≥5) near solar maximum. In comparison, the estimated polar wind ion outflow at times of moderate solar activity is 7×1025H+ and 4×1024 He+ ions s−1. The estimated <10-eV cleft ion fountain flow is 3.8×1025 O+ and 8.6×1023 H+ ions s−1 near solar maximum.