The event on 29–31 October 2003 as an example of processing. Top panel: Magnetic disturbance, H _obs, at the mid-latitude observatories in Table 1 (in colours) and the average of the disturbance 〈H _i 〉 (in black); Second panel: Positive (red) and Negative (blue) Residual Envelopes; Bottom panel: Residual Envelopes range as a proxy for the asymmetry intensity. Grey dashed line marks the SSC in the period plotted.