Signatures of substorm onset in thermodynamic model of geomagnetic tail

Abstract

Earlier, an entropy switch model (ESM) for substorm onset as a result of the development of localized inner magnetospheric interchange-ballooning instability, was suggested. Shown observations testify that the substorm onset is accompanied by the reversal and strong fluctuations in key magnetospheric parameters such as total magnetic field strength, plasma pressure, entropy, and some others. Independently, similar behavior was attributed to a thermodynamic theory, where the onset of a substorm is regarded as a consequence of global energy development in the geomagnetic tail. In the latter, the geomagnetic tail is taken as an open thermodynamic system with an infinite number of conserved energy links (CEL) to the external space environment, and the shaping of the substorm profile is ultimately controlled by the system properties of the tail. A comparison between the signatures of substorm onset in the ESM and CEL models is conducted, and correspondence between experimental data and theoretical results is discussed.