ALBERT

Description: The progress in the mapping of the auroral regions in the Earth's polar ionosphere to outer magnetosphere reflects our growing understanding of the gross magnetospheric structure. Several “natural tracers” were identified and used by us for the mapping scheme advocated for more than a decade. A “natural tracer” is a plasma boundary identifiable at different altitudes which, from physical reasons, is aligned along the magnetic flux tube (accounting for cross-field convection). The boundaries' locations describe the current state of the magnetosphere. The following traccrs to the tail were used in our studies: the low latitude Soft Electron precipitation Boundary; the large-scale Convection Boundary, or an Alfven Layer; the Plasmapause; the Stable Trapping Boundary for high energy electrons; the precipitating hot ion Isotropy Boundary; the two types of Velocity-Dispersed Ion Structures: VDIS-1 (adjacent to an electron inverted-V structure within the oval), and VDIS-2 (just poleward from the oval). A new “Wall Region” concept related to non-adiabatic (non-MHD) ion dynamics allows to add its effects in the list of “natural tracers”. Another newly discovered structure in the tail is the Low Energy Layer of counter-streaming low-energy (〈100 eV) ions and electrons at the outer edge of the Boundary Plasma Sheet. Its physical origin in the far tail, and respective source location, are debatable. Physical limits to the MHD-mapping approach are placed by plasma and field fluctuations and turbulence, by finite Larmor radius effects including non-adiabatic particle dynamics, by finite Alfven propagation times in the magnetosphere, and by various medium-and large-scale disturbances—“auroral activations”. © 1996, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.

Description: A new analysis is described for the published data from the M ASS A active experiments held in 1981-1983 in the USSR. These tests were aimed to simulate earthquake effects in the magnetosphere and ionosphere using surface chemical explosions. Measurements in the magnetosphere above the explosions were made from the AUREOL-3 satellite (Galperin et al1985a1985b). ELF/VLF noises were excited within an altitude range from 410 km to ≈ 2000 km along the Explosion plasma Flux Tube (EFT), based on the .E-region above the explosion point (L ≈ 1.5). During the MASSA-1 experiment, at L ≈ 1.3, before the EFT crossing, 5 minutes after the explosion at L = 1.5, a strong upward moving MHD-impulse was registered with a sharp front. The front was accompanied by excited ion sound waves. Indirect arguments are presented for the origin of the impulse within the EFT, its bouncing and accompanied cross-L drift to, and then trapping at L = 1.3. The effects observed suggest the existence of a natural MHD-impulse generator and/or its power amplifier located in the middle atmosphere not higher than 70 km. It generates/amplifies the electromagnetic response in the magnetosphere and ionosphere. It is suggested that the form of electric discharges in the middle atmosphere known as red sprites or blue jets can serve the role of the natural generator/power amplifier for the effects in the ionosphere and magnetosphere observed in the M ASS A experiments. If real, it can be speculated that similar amplification effects through atmospheric electrical discharges could play a role in the generation of some earthquake precursor effects observed in the magnetosphere and ionosphere.