Effect of large and sharp changes of solar wind dynamic pressure on the earths’s magnetosphere: analysis of several events

The magnetosphere and ionosphere response to arrival of large changes of the solar wind dynamic pressure with sharp fronts to the Earth is considered. It is shown that, under an effect of an impulse of solar wind pressure, the magnetic field at a geosynchronous orbit changes: it grows with increasing solar wind pressure and decreases, when the solar wind pressure drops. Energetic particle fluxes also change: on the dayside of the magnetosphere the fluxes grow with arrival of an impulse of solar wind dynamic pressure, and on the nightside the response of energetic particle fluxes depends on the interplanetary magnetic field (IMF) direction. Under the condition of negative Bz-component of the IMF on the nightside of the magnetosphere, injections of energetic electron fluxes can be observed. It is shown, that large and fast increase of solar wind pressure, accompanied by a weakly negative Bz-component of the IMF, can result in particless’ precipitation on the dayside of the auroral oval, and in the development of a pseudobreakup or substorm on the nightside of the oval. The auroral oval dynamics shows that after passage of an impulse of solar wind dynamic pressure the auroral activity weakens. In other words, the impulse of solar wind pressure in the presence of weakly negative IMF can not only cause the pseudobreakup/substorm development, but control this development as well.