Fig. 2
From: Scale analysis of equatorial plasma irregularities derived from Swarm constellation
a Example of equatorial plasma irregularity (EPI) detected from the electron density observation of Swarm A. The top panel represents the original electron density series (Ne) with 2 Hz resolution, and the bottom panel shows the high-pass filtered and rectified signals. The dashed lines in the bottom panel represent the upper limit (UL) and lower limit (LL) applied for the automatic EPIs detection approach. Frames b and c present two examples of EPIs observed by the three Swarm satellites during the early mission phase. For each event, the top panel represents the original electron density series (Ne) with 2 Hz resolution, the middle panel represents the reconstructed background Ne profil and the bottom panel represents ΔNe with background subtracted