Occurrence and Altitude of the Long‐Lived Nonspecular Meteor Trails During Meteor Showers at High Latitudes

Abstract

AbstractMeteoroids entering the Earth's atmosphere produce ionized trails, which are detectable by radio sounding. Cylindrical underdense (and partly overdense) trails form a great majority of meteor echoes received by meteor radars (MRs). Additionally, the long‐lived nonspecular (LLNS) meteor echoes are received from irregularities of ionization generated along tracks of relatively large meteoroids. At high latitudes where the magnetic field is nearly perpendicular to the Earth's surface the LLNS echoes are possible only from non‐field‐aligned irregularities. The occurrence and height distributions of LLNS echoes are studied using MR observations at the high‐latitude Sodankylä Geophysical Observatory (SGO, 67°22′N, 26°38′E, Finland) during 2008–2019. Two parameters are analyzed: the percentage and height distribution of LLNS echoes. These LLNS echoes constitute about 3% of all MR detections. However, during certain meteor showers (i.e., the Geminids, Perseids, Quadrantids, Arietids or/and Daytime ζ‐Perseids, and Lyrids) the percentage of LLNS echoes is noticeably higher (about 10%, 8%, 7%, 7%, and 4%, respectively). Typically, the LLNSs occur ∼1–2 km higher than other echoes (in June–July the height difference is reduced to ∼0.5–1 km). Moreover, during the Lyrids, η‐Aquariids, Perseids, Orionids, and Leonids the LLNS echoes occur noticeably, up to 3–5 km, higher than the echoes from other types of trails.