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POLAR Observations of Topside Field-Aligned O+ Flows and Auroral FormsMeasurements of thermal O (sup +) ion densities, field-aligned velocities, and fluxes from the Thermal Ion Dynamics Experiment (TIDE) on POLAR obtained near 5000 km altitude over the Southern hemisphere are compared with auroral images from the Ultra Violet Imager (UVI). We find upward O (sup +) flows in the cleft region, but subsonic O (sup +) downflows in the polar cap region. Also, the O (sup +) ion density follows a decreasing trend from the poleward side of the cusp region into the nightside aurora region. The magnitude of the downward O (sup +) parallel velocities increases from dayside to nightside across the polar cap boundary. The upflows tend to occur over or near auroral forms, while the downflows are seen in relatively dark regions, such as the polar cap. These results are consistent with a cleft ion fountain source for the polar cap O (sup +) ions. In the nightside polar cap, the results indicate a transition from downward to upflowing field-aligned O (sup +) ions near boundaries of bright auroral arcs.
Document ID
20000073389
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Stevenson, B. A.
(Alabama Univ. Huntsville, AL United States)
Horwitz, J. L.
(Alabama Univ. Huntsville, AL United States)
Germany, G.
(Alabama Univ. Huntsville, AL United States)
Moore, T. E.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Giles, B. L.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Craven, P. D.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Chandler, M. O.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Su, Y. J.
(Los Alamos National Lab. NM United States)
Parks, G. K.
(Washington Univ. Seattle, WA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Subject Category
Geophysics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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