HR: 15:25h
AN: SA43A-07 INVITED    [Abstracts]
TI: Fundamental Features of Solar Wind-Magnetosphere-Ionosphere Coupling Revealed by High-Latitude Incoherent-Scatter Radars
AU: * Lyons, L R
EM: larry@atmos.ucla.edu
AF: 1Department of Atmospheric and Oceanic Sciences, UCLA, 405 Hilgard Ave., Los Angeles, CA 90095-1565, United States
AU: Zou, S
EM: sha@atmos.ucla.edu
AF: 1Department of Atmospheric and Oceanic Sciences, UCLA, 405 Hilgard Ave., Los Angeles, CA 90095-1565, United States
AU: Heinselman, C
EM: craig.heinselman@sri.com
AF: SRI International, 333 Ravenswood Ave, Menlo Park, CA 94025, United States
AU: Nico, M
EM: michael.nicolls@sri.com
AF: SRI International, 333 Ravenswood Ave, Menlo Park, CA 94025, United States
AU: McCready, M
EM: mary.mccready@sri.com
AF: SRI International, 333 Ravenswood Ave, Menlo Park, CA 94025, United States
AB: Important features of solar wind-magnetosphere-ionosphere coupling can be observed within the ionosphere, where accessibility to ground-based observation allows decoupling of space-time ambiguities that are inherent to spacecraft observations. Incoherent-scatter radars (ISRs) make an important contribution to these ground- based observations by being able to reliably measure plasma flows and electron densities over areas of the ionosphere. These radars have provided critical measurements of the strength and changes of dayside convection imparted to the magnetosphere-ionosphere system by the interplanetary plasma and its changes, as well as of the transfer of polar cap flows to closed field lines that is associated with nightside reconnection. ISR measurement of the nightside flow transfer, complemented by SuperDARN radar observations, provided the first evidence of localized bursts of strongly enhanced nightside convection that lead to auroral poleward boundary intensifications, which are now known to be a major and frequently occurring disturbance of the magnetosphere- ionosphere system. With the recent addition of the ISR at Poker Flat, Alaska, we now have the capability of observing the detailed evolution of electric fields and auroral induced ionization within the nightside auroral oval, which is the ionospheric mapping of the tail plasma sheet. The energy-dependent magnetic drift of plasma sheet ions leads to a divergence of particles, and thus also of cross-tail current. This current divergence leads to the Region 2 field-aligned system and to major changes in magnetosphere-ionosphere convection, which are associated with shielding, formation of the Harang reversal, and are critical to the development of substorms and the stormtime ring current. By combining Poker Flat observations with higher latitude ISR observations, we have implemented a program to observe the Region 2 evolution in response to changes in polar cap convection and initial results show the promise of yielding much new understanding of the evolution of the Region 2 system and its effects on convection
DE: 2407 Auroral ionosphere (2704)
DE: 2411 Electric fields (2712)
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2760 Plasma convection (2463)
DE: 2764 Plasma sheet
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting