The first 10 min interval of Pi2 onset is the most active period of substorms composed of field line deformations associated with an increase in curvature radius of flux tubes and their longitudinal expansion. The flux tube deformations were triggered by the ballooning instability of slow magnetoacoustic waves upon arrival of the dipolarization front from the tail. They preceded the classical dipolarization caused by the reduction of cross-tail currents and resulting pileup of the field lines.

Flow channel extending in north–south directions is produced in the initial pulse of Pi2 pulsations associated with the field line dipolarization. Drifts in the ionosphere of the order of kilometers per second accumulated plasmas at the low-latitude end of the flow channel. The plasma compression in the ionosphere produced field-aligned currents, parallel electric fields, and auroral expansion. We called the compressive ionosphere a "dynamic ionosphere".

The latitudinal structure of the nightside outer magnetosphere of Saturn was studied by using Cassini CAPS plasma measurements. It was found that the plasma density and the azimuthal velocity decrease simultaneously as the spacecraft moves away from the magnetic equator. The magnetosphere exhibits an “onion shell like” structure: the inner regions spin rapidly corotating with the planet, but moving outward and/or further away from the equatorial plane one can encounter slower and slower shells.