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Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitations, Plasma Waves, and Convection Observed by POLARThe POLAR satellite often observes upflowing ionospheric ions (UFls) in and near the auroral oval on southern perigee (approximately 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 dusk side after the substorm onset and then observed a small isolated aurora form and diffuse auroras on the dawn side during the recovery phase. The UFls showed clear conic distributions when the plasma wave instrument (PWI) detected strong broadband wave emissions below approximately 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 approximately 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 (EFI) 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
19990089688
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Hirahara, M.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Horwitz, J. L.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Moore, T. E.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Germany, G. A.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Spann, J. F.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Peterson, W. K.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Shelley, E. G.
(NASA Marshall Space Flight Center Huntsville, AL 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.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Gurnett, D. A.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Persoon, A. M.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Scudder, J. D.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Maynard, N. C.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Mozer, F. S.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Brittnacher, M. J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Nagai, T.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1997
Subject Category
Geophysics
Distribution Limits
Public
Copyright
Other

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