Mesosphere summer echoes observed with VHF and MF radars at Wakkanai, Japan (45.4°N)

► Mesosphere summer echoes (MSE) were observed during 2000-2001 and in 2009 with a VHF radar in Japan. ► MSE appear during equatorward neutral winds that transport cold ice particles from higher latitudes. ► MSE at VHF (VHF-MSE) are often accompanied by MSE at MF (MF-MSE) from a common volume. ► Plasma turbulence and/or electron density structures are responsible for VHF- and MF-MSE occurrences.