Abstract
Correlation between auroral structures and the magnetospheric structures, together with magnetic field conjugacy between the polar ionosphere and the magnetosphere is studied using the magnetic field models proposed by TSYGANENKO and USMANOV (1982) and TSYGANENKO (1987, 1989). The spatial extent where the nightside aurora expands is correlated with the tail plasma sheet, and the magnetospheric sources of radial structures of the dayside aurora are located in the tail flank. It is also shown that these models have a limitation, or rather a systematic error, especially in between the region-1 and region-2 field-aligned current sheets This limitation is due to the fact that the magnetic effects of these field-aligned currents are not consistently taken into consideration in these models. The real footprint of a synchronous satellite estimated by correlating the magnetic field changes at synchronous orbit with an auroral expansion front is deviated 300-400km east of the footprint estimated by these models at the auroral altitude in the dusk sector. At the same time, it is shown that the magnetic field due to the field-aligned current associated with these auroral structures is spatially limited, and, subsequently, is useful for studying the magnetic field congugacy between the polar ionosphere and the magnetosphere.
