Fig. 7
From: Electrodynamics of ionospheric weather over low latitudes
a The local time (UT-3Â h) versus day plot of spread F (ESF) intensity (top panel), and the prereversal drift peak (lower panel) over Fortaleza. The SF intensity is quantified as fop, the top frequency of the range spread F trace. The prereversal vertical drift velocity peak (Vzp) that occurs near 21:00 UT (18:00 LT) and the drift values near 20:50 UT/17:50 LT are also shown for comparison. (b)- Wavelet spectra of the Vzp (near 18:30 LT) over Fortaleza, for which one value per day is used (Abdu et al. 2015a)