Figure 7
Wavelet spectra of the F region prereversal vertical drift velocity peak. The wavelet spectra of the F region prereversal vertical drift velocity peak, Vzp (near 18:30 LT), in which daily values (one value per day) are used. The top panel shows the power spectrum over Fortaleza, and the second (lower) panel shows the result for Sao Luis (600Â km westward of Fortaleza). The lower two panels show the spectra obtained after applying a 3-day smoothing filter to the original daily values. Here, a longer period of around 5-day FK wave may be noted.