MAPPING OF THE PRECIPITATION REGIONS TO THE PLASMA SHEET

The progress in the mapping of the auroral regions in the Earth's pola r ionosphere to outer magnetosphere reflects our growing understanding of the gross magnetospheric structure. Several ''natural tracers'' we re 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 b oundaries' locations describe the current state of the magnetosphere. The following tracers to the tail were used in our studies: the low-la titude Soft Electron precipitation Boundary; the large-scale Convectio n Boundary, or an Alfven Layer; the Plasmapause; the Stable Trapping B oundary 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 VDI S-2 (just poleward from the oval). A new ''Wall Region'' concept relat ed to non-adiabatic (non-MHD) ion dynamics allows to add its effects i n 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 Sh eet. Its physical origin in the far tail, and respective source locati on, are debatable. Physical limits to the MHD-mapping approach are pla ced by plasma and field fluctuations and turbulence, by finite Larmor radius effects including non-adiabatic particle dynamics, by finite Al fven propagation times in the magnetosphere, and by various medium- an d large-scale disturbances-''auroral activations''.