Morris, Ray JamesHoldsworth, David AndrewMurphy, Damian J.Monselesan, D. M.2010-02-012010-02-012005Geophysical Research Letters, 2005; 32(23):23814-238140094-8276http://hdl.handle.net/2440/55965We report on novel spectral characteristics of E-region backscatter acquired using a 1.94 MHz Medium Frequency (MF) radar above the high-latitude Antarctic station Davis (68.6°S). Two distinctive Doppler spectra are observed: one that exhibits bifurcation in Doppler velocity (or frequency) with one, or occasionally more, near symmetrical spectral side-bands (here labelled SSE); and a second that exhibits broad-band spectra related to the magnetic field topology (here labelled FRE). Both spectral forms reveal a characteristic quasi-hyperbolic spectral form that diverges in Doppler velocity with range. We discuss the properties of these two spectral forms including: Doppler spectral shape; power spectra; angle-of-arrival (AOA) of backscattered sources; and their diurnal and day-to-day occurrence distributions for our campaign interval. Interestingly, the E-region SSE observed at a height near 100 km were observed coincidentally with D-region polar mesosphere summer echoes (PMSE) in the height range 82–92 km, when colocated data were available.enJournal article002009208310.1029/2005GL0244290002342472000032-s2.0-31544436859