Effect of the interplanetary magnetic field azimuthal component on dynamics of magnetospheric substorms

The effect of azimuthal component of interplanetary magnetic field (IMF) on the dynamics of magnetospheric substorms is considered. The turning of the azimuthal component of IMF from the positive direction to the negative one and, vice versa, negative and positive impulses in By-component at Bz<0, turning of Bz-component to the North, positive impulses in Bz-component, are investigated. The importance of corresponding variations in magnetic activity level is evaluated. It is shown that turning of By-component from the positive direction to the negative one increases magnetic activity, whereas the reverse transition affects but slightly the level of magnetic activity in the Northern auroral zone. The turning of Bz-component to the North also results in the increase of magnetic activity but with a less intensity than in the case of the negative turning in By-component