A possible mechanism for echo striation generation of radar backscatter from midlatitude sporadic E

The morphological resemblance is described between the quasi-periodic scint illations of VHF radio wave transmissions from a satellite and the 46.5-MHz radar backscatters of the middle and upper atmosphere (MU) radar radio wav es, which are both associated with ionospheric irregularities in the sporad ic E layer. Because these observation techniques are sensitive to different wavelengths of irregularities, the resemblance may be caused by coexisting irregularities. That is, radio wave scintillations reveal medium-scale den sity-enhanced regions with a specific scale length of several hundred meter s in which small-scale irregularities are embedded. The MU radar echoes may reveal backscatter signals from small-scale irregularities. A periodic str ucture on a range-time-intensity (RTI) map reflected the spatial structure of the medium-scale density-enhanced regions. A model is proposed to explai n the striations on the RTI map, which extend up to heights of several tens of kilometers even though sporadic E layers are usually thin.