HR: 12:05h
AN: SM42A-08    [Abstracts]
TI: The distribution of plasma velocity fluctuations observed in the high-latitude ionosphere.
AU: * Bristow, W A
EM: Bill.Bristow@gi.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Dr, Fairbanks, AK 99775, United States
AB: This paper presents a statistical study of the ionospheric plasma velocities observed by the Super Dual Auroral Radar Network (SuperDARN) HF radar network. The study was undertaken with the goal of determining the level of velocity fluctuations due to internal magnetospheric processes. A secondary goal was to examine the probability of observing significant velocity fluctuations within any given time interval. The study included six years of observations from periods when the interplanetary magnetic field (IMF) was moderately southward and steady. The choice of such conditions was motivated by the goal of examining internal sources of variability and sought periods when the fluctuations of the main external driver, the IMF, were minimized. Inherent in this study is the assumption that the IMF that encounters the magnetosphere is the same as that observed at a spacecraft located upstream from the Earth, and that all variability of the plasma convection is due either to variability of the IMF driver or to internal magnetospheric processes. For the purposes of this study, structure of the solar wind and IMF away from the satellite cannot be accounted for, and variability generated at the bow shock is considered to be an internal magnetospheric process. IMF variability away from the satellite was examined by comparing observations for the ACE and Wind satellites. The distribution of velocity fluctuations and their waiting time distribution were examined over a grid of latitude and local time. It was found that the waiting time is scale free over the range of times that could be examined. From the waiting time distributions, the probability of observing fluctuations within various time intervals was determined over the grid.
DE: 2411 Electric fields (2712)
DE: 2712 Electric fields (2411)
DE: 2740 Magnetospheric configuration and dynamics
DE: 2760 Plasma convection (2463)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting