HR: 17:30h
AN: SA32B-07    [PDF]
TI: Search for Thermospheric Composition Changes in the Morning Sector near Local Midnight in Association with Intense Substorm Activity
AU: * Craven, J D
EM: craven@gi.alaska.edu
AF: Geophysical Institute and Dept. of Physics, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Strickland, D J
EM: dstrick@cpi.com
AF: Computational Physics, Inc., 8001 Braddock Rd., Suite 210, Springfield, VA 22151 United States
AU: Meier, R R
EM: meier@uap2.nrl.navy.mil
AF: E. O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, D.C 20375 United States
AU: Crowley, G
EM: gcrowley@swri.edu
AF: Southwest Research Institute, Space Physics Dept., 6220 Culebra Rd., San Antonio, TX 78238 United States
AU: Christensen, A B
EM: Andrew.B.Christensen@aero.org
AF: The Aerospace Corporation, PO Box 92957, Los Angeles, CA 90009 United States
AU: Paxton, L J
EM: larry.paxton@jhuapl.edu
AF: JHU/Applied Physics Laboratory, 11100 John Hopkins Road, Laurel, MD 20723 United States
AU: Morrison, D
EM: danny.morrison@jhuapl.edu
AF: JHU/Applied Physics Laboratory, 11100 John Hopkins Road, Laurel, MD 20723 United States
AU: Avery, S K
EM: savery@cires.colorado.edu
AF: CIRES, 216 University of Colorado, Boulder, CO 80309 United States
AU: Meng, C -
EM: ching.meng@jhuapl.edu
AF: JHU/Applied Physics Laboratory, 11100 John Hopkins Road, Laurel, MD 20723 United States
AU: Straus, P R
EM: paul.straus@aero.org
AF: The Aerospace Corporation, PO Box 92957, Los Angeles, CA 90009 United States
AU: Swenson, C M
EM: charles.swenson@usu.edu
AF: Utah State University, Dept. of Electrical and Computer Engineering, 4120 Old Mail Hill, Logan, UT 84322 United States
AU: Walterscheid, R L
EM: walterscheid@eumetsat.de
AF: The Aerospace Corporation, PO Box 92957, Los Angeles, CA 90009 United States
AB: Repeated DE-1 and other spacecraft observations have established that transient decreases in the far-ultraviolet (FUV) terrestrial OI emissions at subauroral latitudes in the morning sector are associated with decreases in the O/N2 ratio at thermospheric altitudes. The largest decrease is at 130.4 nm. These decreases are observed following onset of intense auroral activity, and at northern latitudes the greater spatial extent and depth of decrease are associated with a positive IMF By component. The DE-1 viewing geometry generally precluded clear observations in the morning sector at local solar times earlier than about 0600 hours. However, it is believed that the altered composition is driven by aurorally related heating and the antisunward polar jet that transports heated air to subauroral latitudes in the very early hours of local time and then into the morning sector. FUV observations of altered composition closer to local midnight are lacking, but are necessary to support this general expectation. The GUVI observations at FUV wavelengths are providing an extensive new set of unambiguous thermospheric composition and temperature measurements over a wide range of local times and latitudes in both auroral hemispheres as the orbit of the near-polar-orbiting TIMED spacecraft processes rapidly in local time. These data are being scanned in a search for the requisite combination of sampling at the right local times in periods of auroral substorms to address the question of composition changes near local midnight. A report on this search and its findings are presented in this paper.
DE: 0310 Airglow and aurora
DE: 0355 Thermosphere--composition and chemistry
DE: 7549 Ultraviolet emissions
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting