MSTID extraction from more frequent ionograms

The paper shows the possibility of rapid extraction from more frequent ionograms not only strong medium-scale traveling ionospheric disturbances (MSTIDs) in the F region in the form of cusps and hooks, but also weak MSTIDs, whose form may differ from the cusp (hook) shaped. To isolate these MSTIDs will be enough to follow the slope of the F layer cusp (about the critical frequency). Another important feature is the lowering of the ordinary cusp below extraordinary one and vice versa. New stable parameter based on the differential rotation of the trace and characterized the activity of weak MSTIDs was proposed.