Abstract
Abstract. Considering the magnetic reconnection and the viscous interaction as the fundamental mechanisms for transfer particles and energy into the magnetosphere, we study the dynamical characteristics of auroral electrojet (AE) index during high-intensity, long-duration continuous auroral activity (HILDCAA) events, using a long-term geomagnetic database (1975–2012), and other distinct interplanetary conditions (geomagnetically quiet intervals, co-rotating interaction regions (CIRs)/high-speed streams (HSSs) not followed by HILDCAAs, and events of AE comprised in global intense geomagnetic disturbances). It is worth noting that we also study active but non-HILDCAA intervals. Examining the geomagnetic AE index, we apply a dynamics analysis composed of the phase space, the recurrence plot (RP), and the recurrence quantification analysis (RQA) methods. As a result, the quantification finds two distinct clusterings of the dynamical behaviours occurring in the interplanetary medium: one regarding a geomagnetically quiet condition regime and the other regarding an interplanetary activity regime. Furthermore, the HILDCAAs seem unique events regarding a visible, intense manifestations of interplanetary Alfvénic waves; however, they are similar to the other kinds of conditions regarding a dynamical signature (based on RQA), because it is involved in the same complex mechanism of generating geomagnetic disturbances. Also, by characterizing the proper conditions of transitions from quiescent conditions to weaker geomagnetic disturbances inside the magnetosphere and ionosphere system, the RQA method indicates clearly the two fundamental dynamics (geomagnetically quiet intervals and HILDCAA events) to be evaluated with magneto-hydrodynamics simulations to understand better the critical processes related to energy and particle transfer into the magnetosphere–ionosphere system. Finally, with this work, we have also reinforced the potential applicability of the RQA method for characterizing nonlinear geomagnetic processes related to the magnetic reconnection and the viscous interaction affecting the magnetosphere.
Highlights
A complicated electrodynamic region populated by plasmas and ruled by the Earth’s magnetic field – designated in a classical definition as magnetosphere – exists surrounding our planet (Mendes et al, 2005; Kivelson and Russell, 1995)
To pursue a comprehensive answer, we apply the recurrence quantification analysis (RQA) methodology to all 80 HILDCAA events completed by the examination of other cases selected to allow comparisons
Obtained from a diagnosis of features of a nonlinear system analysis, a physics scenario of the auroral electrojet (AE) index is built with the aid of the recurrence quantification analysis (RQA) information extracted from the recurrence plot (RP) calculation
Summary
A complicated electrodynamic region populated by plasmas and ruled by the Earth’s magnetic field – designated in a classical definition as magnetosphere – exists surrounding our planet (Mendes et al, 2005; Kivelson and Russell, 1995). The most intense is through the magnetic reconnection process (Burch and Drake, 2009; Kivelson and Russell, 1995; Dungey, 1961), when the interplanetary magnetic field (IMF) presenting a predominantly southward orientation, in the geocentric solar magnetosphere reference system, merges into the geomagnetic field at the outer boundary and produces strong modification in a large region formed by the magnetosphere and the ionosphere – the latter is a region from about 100 to 2000 km of altitude presenting the highest quantity of ionized particles Another competitive process is the Kelvin–Helmholtz viscous interaction (Hasegawa et al, 1997; Chen et al, 2004; Axford and Hines, 1961). The former process is more efficient in energy and particle transfer than the latter one
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