“…It should be noted, however, that at all topside TEC values there are profiles with an a-Chapman shape. This is to be expected, since the data was taken at all possible local times and seasons and at different magnetic longitudes and latitudes; it is well known that the storm time behaviour at different times and location can be very different (Ondoh, 1967;Sato, 1968;Warren, 1969;Fuller-Rowell et al, 1994;Kutiev and Muhtarov, 2001), and it should be noted that a TEC value that is considered depleted at certain times and locations might be a normal, quiet time value at others (Kutiev et al, 2005;2006b). The same issues exist with regard to the topside slab thickness (defined as the topside TEC divided by the peak electron density), which are displayed in Fig.…”