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Observations of ion-neutral collisional effects in the auroral E regionThermal ion energy distribution functions and local electric and magnetic fields were directly measured for the first time in the ionospheric E region. Measured ion distribution functions were fitted to shifted Maxwellian distributions, and their resulting ion drift velocities were compared with E x B/B-squared velocities from the double-probe electric field observations. The results show that the ion drift direction rotates with respect to the local electric field direction and that the ratio of the magnitudes of the ion velocity to the E x B/B-squared velocity decreases with decreasing altitudes. Using these observations, the quiet time ion-neutral collison frequencies and neutral wind velocities were estimated and found to be consistent with theoretical estimates. However, significant discrepancies between observations and theory are found in the disturbed E region near auroral particle precipitation regions. These data indicate that the auroral atmosphere is significantly perturbed due to Joule as well as particle heating effects.
Document ID
19910055781
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Watanabe, S.
(Herzberg Inst. of Astrophysics Ottawa Ontario, Canada)
Whalen, B. A.
(Herzberg Inst. of Astrophysics Ottawa Ontario, Canada)
Wallis, D. D.
(National Research Council of Canada Herzberg Institute of Astrophysics, Ottawa, United States)
Pfaff, R. F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 15, 2013
Publication Date
June 1, 1991
Publication Information
Publication: Journal of Geophysical Research
Volume: 96
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
91A40404
Distribution Limits
Public
Copyright
Other

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