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Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitation, Plasma Waves, and Convection Observed by PolarThe POLAR satellite often observes upflowing ionospheric ions (UFIs) in and near the aurora] oval on southern perigee (approx. 5000 km altitude) passes. We present the UFI features observed by the thermal ion dynamics experiment (TIDE) and the toroidal imaging mass angle spectrograph (TIMAS) in the dusk-dawn sector under two different geomagnetic activity conditions in order to elicit their relationships with auroral forms, wave emissions, and convection pattern from additional POLAR instruments. During the active interval, the ultraviolet imager (UVI) observed a bright discrete aurora on the duskside after the substorm onset and then observed a small isolated aurora form and diffuse auroras on the dawnside during the recovery phase. The UFIs showed clear conic distributions when the plasma wave instrument (PWI) detected strong broadband wave emissions below approx. 10 kHz, while no significant auroral activities were observed by UVI. At higher latitudes, the low-energy UFI conics gradually changed to the polar wind component with decreasing intensity of the broadband emissions. V-shaped auroral kilometric radiation (AKR) signatures observed above -200 kHz by PWI coincided with the region where the discrete aurora and the UFI beams were detected. The latitude of these features was lower than that of the UFI conics. During the observations of the UFI beams and conics, the lower-frequency fluctuations observed by the electric field instrument were also enhanced, and the convection directions exhibited large fluctuations. It is evident that large electrostatic potential drops produced the precipitating electrons and discrete auroras, the UFI beams, and the AKR, which is also supported by the energetic plasma data from HYDRA. Since the intense broadband emissions were also observed with the UFIs, the ionospheric ions could be energized transversely before or during the parallel acceleration due to the potential drops.
Document ID
19990039172
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hirahara, M.
(Alabama Univ. Huntsville, AL United States)
Horwitz, J. L.
(Alabama Univ. Huntsville, AL United States)
Moore, T. E.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Germany, G. A.
(Alabama Univ. Huntsville, AL United States)
Spann, J. F.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Peterson, W. K.
(Lockheed Martin Missiles and Space Palo Alto, CA United States)
Shelley, E. G.
(Southwest Research Inst. San Antonio, TX United States)
Chandler, M. O.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Giles, B. L.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Craven, P. D.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Pollock, C. J.
(Southwest Research Inst. San Antonio, TX United States)
Gurnett, D. A.
(Iowa Univ. Iowa City, IA United States)
Pickett, J. S.
(Iowa Univ. Iowa City, IA United States)
Persoon, A. M.
(Iowa Univ. Iowa City, IA United States)
Scudder, J. D.
(Iowa Univ. Iowa City, IA United States)
Maynard, N. C.
(Mission Research Corp. Nashua, NH United States)
Mozer, F. S.
(California Univ. Berkeley, CA United States)
Brittnacher, M. J.
(Washington Univ. Seattle, WA United States)
Nagai, T.
(Tokyo Inst. of Tech. Tokyo, Japan)
Date Acquired
August 19, 2013
Publication Date
August 1, 1998
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 103
Issue: A8
ISSN: 0148-0227
Subject Category
Geophysics
Report/Patent Number
Paper-97JA02668
Funding Number(s)
CONTRACT_GRANT: NAS5-30302
CONTRACT_GRANT: NAS5-30367
PROJECT: SwRI Proj. 15-9455
CONTRACT_GRANT: NAG8-114
CONTRACT_GRANT: NAS8-38145
CONTRACT_GRANT: NAS8-38189
CONTRACT_GRANT: NAS5-30371
PROJECT: GGS Proj. UDN 370-17-43
CONTRACT_GRANT: NAS8-38145
CONTRACT_GRANT: NAG5-3182
CONTRACT_GRANT: NAG8-693
CONTRACT_GRANT: NAS8-38146
Distribution Limits
Public
Copyright
Other

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