HR: 10:20h
AN: SM12A-01 INVITED    [Abstracts]
TI: Some Consequences of Penetration Electric Fields
AU: * Huang, C Y
EM: cheryl.huang@hanscom.af.mil
AF: AFRL/VSBXP, 29 Randolph Road, Hanscom AFB, MA 01731, United States
AU: Burke, W J
EM: william.burke2@hanscom.af.mil
AF: AFRL/VSBXP, 29 Randolph Road, Hanscom AFB, MA 01731, United States
AB: During the main phases of geomagnetic storms penetration electric fields profoundly affect the dynamics of the inner magnetosphere as well as the mid- to low-latitude ionosphere. We derive a modified Volland-Stern model driven by plasmas and fields measured near L1 that predicts the strength of electric fields in the inner magnetosphere. A priori, values of the model's shielding parameter are unknown. However the spatial and temporal variability of equatorial plasma bubbles observed by DMSP satellites in the low-latitude ionosphere provide indirect, but compelling evidence that during that main phase of most storms electric fields remain unshielded. Penetration electric fields can persist for hours, not minutes. This empirical conclusion has major implications for estimating drift paths available to ring-current ions and modeling the dynamics of plasma plumes that extend from the dayside plasmasphere to the magnetopause. The presence of cold plasma through unusual locations in the outer magnetosphere in turn affects the growth rates of waves responsible for precipitation into the dayside ionosphere. Finally, we show that time-integrals of Volland-Stern electric fields are highly correlated with the development of main-phase Dst and hence with the total energy budget of current carrying particles in the plasma sheet and inner magnetosphere. .
DE: 2712 Electric fields (2411)
DE: 2730 Magnetosphere: inner
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting