MULTI-POINT GROUND OBSERVATIONS AND MODELLING OF SUBSTORM CHORUS EVENTS

摘要

Electrons injected into the nightside magnetosphere during the expansion phase of a substorm generate whistler-mode waves near the equator which propagate downwards along field-aligned paths and through the ionosphere to be observed on the ground as substorm chorus events (SCEs). We present observations of such events, recorded in Antarctica at Halley station (L ～ 4) and the British Antarctic Survey's AGOs (Automatic Geophysical Observatories), located polewards of Halley. The receiver at each station measures wave power, polarisation and arrival azimuth of the SCE in each of a number of frequency bands. We can use these observations as a function of time from the substorm expansion pkase onset, combined with a full-wave code to model the propagation of the waves through and under the ionosphere, to estimate the apparent position and motion of the regions where the SCE waves enter the Earth-ionosphere waveguide. This can then be related to the evolution of the wave generation region as the substorm progresses.