Polar Mesosphere Summer Echoes and Possible Signatures of Pulsating Aurora Detected by the Meteor Radar

Abstract

Polar mesospheric summer echoes (PMSE) are a form of radar backscatter from electron density irregularities occurring in the high-latitude summer mesosphere at altitudes between 80 and 90 km, in the vicinity of the mesopause. In most cases, PMSE observations have been made with VHF (very high frequency, 30-300 MHz) radars, which implies backscatter from few meters scale irregularities. It is commonly accepted that the formation of such irregularities is associated with the ice particles existing in the cold summer mesosphere (e.g., Rapp & Lübken, 2004). Mechanisms for the formation of PMSE will be discussed in more detail in Section 4. Almost all previous PMSE studies have been performed with a time resolution of the order of one minute to few seconds. To our knowledge, only one study using PMSE observations on the subsecond scale have been published (Sommer et al., 2016). These observations were made during two experimental campaigns, and two cases of PMSE were investigated with 2-ms temporal sampling and down to 75-m range resolutions. It