A damped linear oscillator (LRC circuit) predicts a significant amount of the AL index variations when it is driven by the IMF's BSouth component. The model parameters are determined from fitting the AL time series and show a small, apparently nonsystematic variation with the activity level. Following an isolated external disturbance the LRC model's response peaks at 15 min -0.5 h and decays after 1--2 more hours. The time scales and the correlation between observed AL and the circuit output (60--80%) are in good agreement with earlier linear prediction filter results. The results support the modeling of the global magnetospheric behavior with dynamical systems of a few degrees of freedom. ¿ American Geophysical Union 1993