Investigating the correlation between Flat Top Solitary Waves and Offset Bipolar Pulse in auroral plasma

Abstract

Non conventional localized pulses, like offset bipolars have been reported in the Earths magnetosphere. The reports were sporadic and the theoretical interpretations were mainly event based which differ for slow or fast moving pulses. Here it was shown that the offset bipolar pulses are manifestations of an ideal, mathematically defined nonlinear coherent structure called a flat top soliton. Adopting Sagdeev pseudopotential technique, and assuming a simple plasma model, it was shown that a slow moving offset bipolar pulse in the auroral region can be interpreted as an ion acoustic flat top solitary wave. The proposed theory is a generic one and can easily be extended to a fast moving one under an appropriate plasma model. One important characteristic of such structures is that they generally occur at the boundary of two different phases of nonlinear dynamical processes.