Conjugate Observations of Magnetospheric and Ionospheric Phenomena During a Substorm Event

Abstract

This study investigates the comprehensive magnetospheric and ionospheric phenomena during a substorm event on 14 December 2013. The methodology involves analyzing data from satellites located within the plasmasphere at dusk-side of the Earth, as well as data from ionospheric satellites mapped in the subauroral region. Magnetospheric data were analyzed to identify key features during the substorm event. Proton injection into the ring current, presence of proton and helium band electromagnetic ion cyclotron (EMIC) waves with different polarization characteristics, and harmonic structures in these EMIC waves were identified. These harmonic structures coincided with the appearance of magnetosonic waves characterized by rising tone structures and heating of low-energy protons (<100 eV). Ionospheric satellites (DMSP F17 and POES 15) recorded enhanced proton precipitation contributing to the intensification of subauroral proton arcs. The analysis revealed that these enhanced proton fluxes were associated with variations in field-aligned currents (FACs) and drove dynamics within the Sub-Auroral Polarization Streams (SAPS). By combining and analyzing the magnetospheric and ionospheric data sets, this study provides a comprehensive understanding of magnetosphere-ionosphere coupling during substorms, particularly on the duskside. The complex interdependence and causal relationships among EMIC waves, proton precipitation, subauroral proton arcs, FAC variations, and SAPS dynamics were highlighted.