On the Sources, Coupling and Energetics During Supersubstorms of the Solar Cycle 24

Abstract

AbstractThe solar cycle 24 exhibited only four supersubstorms (SSSs) during three of the geomagnetic storms of May 2011, March 2012, and September 2017. A robust and quantitative analyses of these events is performed and the results show that multiple hits by the magnetic clouds with fast moving background solar wind plasma provided the conditions for occurrence of these events. The available solar wind energy, the magnetospheric input energy and the sink energies are estimated. The input energy dominates the total dissipation for shorter intervals of the SSSs, wherein, a dominance of Joule heating sink over the auroral particle precipitation and ring current sinks is revealed. However, for longer time intervals (6 months and more), the total dissipation supersedes the total input energy wherein, the auroral precipitation sink dominates. The contribution of the ring current sink is found at the lowest levels against a high percentage share (79%–91%) of ionospheric sink during the SSSs. Intriguingly, when the SSS expansion and the recovery phases are compared on dissipation terms, percentage share of the Joule heating (ring current) is found more during the later (former) phase. The input efficiencies are found at ∼3.05%, 4.95%, 3.98%, and 1.15%, and the dissipation efficiencies at 73.95%, 58.56%, 37.72%, and 77.94%, respectively during the four SSSs. The dissipation efficiency and the ratio of the sink energies are found to be inversely proportional to the intensity of the substorms. The energy partitioning in the magnetosphere‐ionosphere system also respond in a contrasting fashion to the different levels of substorms.