Interchange instability related to the azimuthal pressure gradient as a possible mechanism of substorm intensification

An increase in the interchange instability, related to the azimuthal pressure gradient of the magnetospheric plasma, in the region of an expected substorm center is numerically simulated in this work. It is ascertained whether this instability can trigger substorm intensification at the stage of strong nonlinearity. An attempt is made to reproduce the main features in the breakup arc dynamics at a transition to the substorin expansion phase.