Initial observations of polar mesospheric summer echoes using the EISCAT Svalbard radar

Polar Mesospheric Summer Echoes (PMSE) have been observed at various freque ncies from MF to UHF and at various latitudes. Here, we report the observat ion of PMSE over Svalbard (79 degreesN) at 500 MHz. Although PMSE have been reported earlier at such high latitude at VHF (notably around 50 MHz), the y had hitherto not been reported at such high frequency as 500 MHz. Further more, this observation represents the first one using a frequency between 2 24MHz and 933MHz. The PMSE scattering mechanism is still open to debate and is certainly frequency dependent: the new observations at 500 MHz will hel p to identify the transition frequency between different mechanisms.