Effects of the Ring Current Decay Rate on the Energy State of the Magnetosphere

Abstract

AbstractGeomagnetic storms are mainly caused by the ring current, the decay rate of which is one of the key parameters for estimating energy budget of the magnetosphere and for storm prediction. Two new criterions are suggested in this paper for evaluating decay rate models: (1) the E‐criterion: the total energy balance for a storm event, or balance between the integrated energy input and output during whole course of the event; (2) the L‐criterion: the total energy balance for a long interval, or balance between the integrated energy input and output for a sufficiently long time span. Nine decay rate models are examined by using 44 selected storms during 1998~2003 and using an 11‐year‐long continuous record for the 23rd solar cycle (1998~2008). The results show that the models PA1978 and XD2010 show fairly good energy balance for all studied events, satisfying the E‐criterion. In addition, the two models rather well satisfy the L‐criterion, exhibiting enhanced energy dissipation during major storm events and long‐term energy balance.