HR: 09:45h
AN: SA21A-08    [PDF]
TI: Implications of results from the HEX sounding rocket mission
AU: * Conde, M G
EM: mark.conde@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Craven, J D
EM: john.craven@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Larsen, M F
EM: mlarsen@clemson.edu
AF: Physics and Astronomy Department Kinard Laboratory, Clemson University, Clemson, SC 29634-1911 United States
AU: Wescott, E M
EM: gene.wescott@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Stenbaek nielsen, H
EM: hans.nielsen@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Lummerzheim, D
EM: dirk.lummerzheim@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Johnson, B A
EM: baj@gci.net
AF: Department of Electrical Engineering University of Alaska Fairbanks, Box 751841, Fairbanks, AK 9975 United States
AU: Hawkins, J G
EM: ffjgh@uaf.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AU: Smith, R W
EM: roger.smith@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, AK 99775 United States
AB: Numerous ground and space-based measurements have shown that the aurora modifies thermospheric composition by increasing, relative to diffusive equilibrium, the mixing ratio of heavy molecular species at higher altitudes. The presumed mechanism for this mixing has been vertical wind circulation driven by the aurora. However, prior to the HEX rocket mission, no experiment had ever tested this hypothesis by mapping the actual vertical wind field in the E-region near an individual auroral arc. With HEX, we measured the vertical wind as a function of latitudinal distance from a pair of quiet pre-midnight arcs, using a visible chemical trail deployed along a novel near-horizontal trajectory. Instruments aboard the rocket also observed the in-situ electron density and the auroral luminosity. The measurements were of high quality, and their outcome was clear: The hypothesis was false. No upwelling and no significant mixing were occurring due to this particular system of quiet arcs. Assuming these results are typical, HEX demonstrated that quiet pre-midnight arcs play little role in mixing the thermosphere. With its successful characterization of quiet-time "baseline" conditions, HEX now gives us the tool to study active post-midnight aurora that likely does drive the mixing that has been observed.
DE: 2407 Auroral ionosphere (2704)
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 3369 Thermospheric dynamics (0358)
DE: 3394 Instruments and techniques
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting