A two-step scenario for both solar flares and magnetospheric substorms: Short duration energy storage

Abstract

The basic observations for magnetic storms and substorms at Earth and for flares at the Sun are reviewed for background. We present a common scenario of double magnetic reconnection for both substorms and flares based on previous interplanetary observations and substorm-triggering results. Central to the scenario is that the first magnetic reconnection phase is the source of energy loading for possible substorms and flares. The energy placed in the magnetotail or magnetosphere at the sun lasts for only a short duration of time however. The energy gets dissipates away rapidly (in some less dramatic form). This scenario predicts that if the initial reconnection process is sufficiently intense and rapid, concomitant substorms and flares occur soon thereafter. If the energy input is less rapid, there may be lengthy delays for the onset of substorms and flares. If external influences (shocks, etc.) occur during the latter energy buildup, the "trigger" will cause a sudden release of this energy. The model also explains reconnection without subsequent substorms and flares. The model addresses the question why strong triggering events are sometimes ineffective. Copyright © The Society of Geomagnetism and Earth.