Planetary Distribution of Auroral Precipitation and Its Relation to the Zones of Auroral Luminosity

摘要

Boundaries of different auroral precipitation have been determined based on data of the DMSP F6 and F7 satellites. The boundaries of auroral precipitation on the day and night sides of the Earth have been joined proceeding from the new terminology of electron precipitation [Starkov et al., 2002]. The planetary pattern of precipitation at different levels of magnetic activity has been constructed. It has been indicated that the auroral oval precipitation (AOP) spatially coincides with the auroral oval. The zones of diffuse precipitation (diffuse auroral zone. DAZ) and diffuse auroral luminosity coincide at low and moderate magnetic activity. At high magnetic activity, the low-latitude auroral edge is sometimes observed equatorward of the corresponding precipitation boundary. The dynamics of the narrow belt of soft diffuse precipitation (SDP), located poleward of the auroral oval, has been studied. It has been indicated that, at low magnetic activity, this precipitation surrounds the AOP one in the form of a belt with a width of ～2°in latitude. With increasing magnetic activity, this belt becomes narrower and disappears on the nightside at |AL| > 400 nT. The polar cap boundaries have been determined. It has been indicated that the polar cap area linearly increases with increasing magnetic activity. At high magnetic activity (|AL| > 400 nT), the polar cap area is twice as large as under quiet conditions. The growth of magnetic disturbance results in a synchronous widening and simultaneous equatorward shift of the zones of auroral luminosity and precipitation.