Estimation of decay time of the November 20, 2003 superstorm ring current

The decay time of DR-current τT has been calculated in discrete 5-min steps using 20.11.2003 superstorm data. The well-known Dessler-Parker-Scopke equation and SYM-H indices are used. QDR values of DR current power are determined on the basis of new method in which QDR=ε' - Qi. Input power ε' and storm power Qi in the ionosphere are calculated using the mag-netogram inversion technique (TIM-2). The τT values are compared with τ0 and τG values calculated from two basic known empirical models. The time τT varies from ~10 min to ~2 h during the superstorm and correlates with the observed variations of superstorm six regimes selected before. Values of τ0 и τG differ from τT a few times. They differ still more between themselves and their variations during the storm (especially τ0) do not correlate with the observed variations of substorm regimes. The empirical scale τ for seven different regimes of magnetospheric disturbance was first obtained.