RING CURRENT AND AURORAL ELECTROJETS IN CONNECTION WITH INTERPLANETARY MEDIUM PARAMETERS DURING MAGNETIC STORM

The relationship between the auroral electrojet indices (AE) and the r ing current magnetic field (DR) was investigated by observations obtai ned during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral ele ctrojets toward the equator. As a result, the standard AE indices calc ulated on the basis of data from auroral observatories was substantial ly lower than the real values (AE'). To determine AE' during the cours e of a storm main phase data from subauroral magnetic observatories sh ould be used. It is shown that the intensity of the indices (AE') whic h take into account the shift of the electrojets is increased substant ially relative to the standard indices during the storm main phase. AE ' values an closely correlated with geoeffective solar wind parameters . A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic fi eld variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken i nto account. This applies both to case studies and statistical data. T he dynamics of the electrojets in connection with the development of t he ring current and of magnetospheric substorms can be described by th e presence (absence) of saturation for minimum (maximum) AE index valu es during a 1-h interval. The ring current magnetic held asymmetry (AS Y) was calculated as the difference between the maximum and minimum fi eld values along a parallel of latitude at low latitudes. The ASY valu e is closely correlated with geoeffective solar wind parameters and si multaneously is a more sensitive indicator of IMF B-z variations than the symmetric ring current. ASY increases (decreases) faster during th e main phase (the recovery phase) than DR. The magnetic field decay at low latitudes in the recovery phase occurs faster in the afternoon se ctor than at dusk.