“…One way was to select rare events with good constellations of magnetospheric spacecraft and, in addition, to use magnetic measurements obtained during an extended time period (using data obtained during times when the configuration remained steady, e.g., during steady convection (SMC) event, or by approximating the temporal variations by linear change of model parameters during the substorm growth phase). This was the approach used previously in the modeling of the substorm growth phase [Pulkkinen et al, , 1994a] of the substorm recovery phase [Pulkkinen et al, 1994b] and of the SMC event [$ergeev et al, 1994]. Unfortunately, good spacecraft constellations (with at least three to four spacecraft favorably distributed across the transition region) are very rare, and the suggestion of linear changes during any particular event is difficult to evaluate and justify.…”