In 99% of cases, substorms precede steady magnetospheric convection


  • Colin Schultz


Previous research on two types of magnetospheric activity—magnetic substorms and steady magnetospheric convection (SMC)—suggested that a substorm might be a necessary condition for the onset of SMC. Building on that work, Kissinger et al. determined the strength of the connection between the two modes of activity. Researchers previously showed that when the solar wind interacts with the Sun-facing terrestrial magnetic field, magnetic reconnection can drive magnetic field lines to break and magnetospheric plasma to be swept around to the Earth's nightside. When the magnetic field lines reconnect in the magnetotail, the most common reaction is for the nightside magnetosphere plasma to be sent Earthward in an event known as a magnetic substorm. In some cases, however, SMC can occur. During SMC, the plasma is diverted by a high-pressure region in the inner magnetotail so that it does not stay piled up on the nightside but instead travels around the planet's flanks. Earlier research suggested that such high-pressure regions are caused by magnetic substorms, which led the researchers to suggest that substorms are necessary to drive SMC activity.