HR: 17:45h
AN: SM52E-08    [PDF]
TI: Wave Contributions to Coupling Between the Ring Current/Plasmasphere and Subauroral Ionosphere
AU: Gentile, L C
EM: louise.gentile@hanscom.af.mil
AF: Boston College, Institute for Scientific Research, Chestnut Hill, MA 02467 United States
AU: Burke, W J
EM: bill.burke@hanscom.af.mil
AF: AFRL/VSBXP, 29 Randolph Rd, Hanscom AFB, MA 01731 United States
AU: * Mishin, E V
EM: evgenii.mishin@hanscom.af.mil
AF: Boston College, Institute for Scientific Research, Chestnut Hill, MA 02467 United States
AB: It has long been established that strong electric fields at subauroral latitudes in the post-sunset sector enable ionospheric closure of field-aligned currents generated in the stormtime ring current. Recent observations by the DMSP satellites of $\sim$10-km scale plasma density and electromagnetic oscillations, within the region of strong electric fields, indicate efficient M-I coupling in the ring current-plasmasphere overlap. It is demonstrated that a feedback instability may develop, analogous to that found in the auroral ionosphere. Enhanced electric fields and large-scale density troughs are the necessary conditions for the feedback to develop. Usually density troughs collocated with strong electric fields are viewed as consequences of frictional ion heating causing plasma outflow and increased rates of recombination stemming from charge exchange/transfer. This paper reports observations from DMSP satellites that are not fully described by this conventional model. During some strong subauroral wave-structure events, density troughs coincide with electron temperature enhancements, while the electric fields and ion temperatures are barely perturbed from background values. No significant ion outflows occur. Our observations suggest additional requirements for describing these subauroral dynamics. In addition to the conventional model, we account for strong electron heating in the ring current-plasmasphere overlap region. Resultant electron heat fluxes lead to the vibrational excitation of molecular nitrogen and support enhanced rates of charge exchange/transfer and recombination.
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2471 Plasma waves and instabilities
DE: 2778 Ring current
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting