HR: 1330h
AN: SM42A-0596    [PDF]
TI: Transient Sheets of Field-Aligned Currents Observed During a Superstorm
AU: * huang, c y
EM: cheryl.huang@hanscom.af.mil
AF: ISR, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 United States
AU: burke, w j
EM: william.burke2@hanscom.af.mil
AF: Space Vehicles Directorate, Air Force Research Laboratory, Hanscom AFB, MA 01731 United States
AB: During the main phase of the superstorm on 6 April 2000 (Dst $<$ -200 nT), multiple DMSP satellites observed large sheets of field-aligned currents (FACs) in both hemispheres and at local times ranging from dawn to 09:00 and from dusk to 21:00 LT. FAC intensities (J $>$ 1 A/m) are amongst the largest ever observed by DMSP, yet produced no commensurate magnetic signatures on the ground beneath or magnetically conjugate to the satellites. The event empirically confirms Fukushima's theorem. In addition, Pedersen conductances required by Ohm's law are much larger than values estimated with Robinson's formula. Particle and field observations during the event show that precipitating low-energy electrons and ring-current ions are the primary FAC carriers in the upward and downward sheets. Neglect of their contributions can lead to significant underestimates of conductance. Our results have profound relevance for understanding magnetosphere-ionosphere coupling and the dissipation of ring-current energy under highly stressed geomagnetic conditions.
DE: 2411 Electric fields (2712)
DE: 2708 Current systems (2409)
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting