High-latitude MSTIDs over the EISCAT-3D site: Solar activity and seasonal dependency

Abstract. This work involves an investigation of high-latitude medium scale traveling ionospheric disturbances (MSTIDs) over the newly established EISCAT-3D radar site. We have used the ground backscatter data from an HF radar located at Hankasalmi, Finland (~62.3° N, ~26.61° E geographic coordinates), which is a part of the SuperDARN (Super Dual Auroral Radar Network). Data from solar maximum (2001 & 2014) and minimum (1996 & 2009) years from solar cycles 23 and 24 have been used to investigate the characteristics, seasonal variation, and possible generating sources of high-latitude daytime MSTIDs. Irrespective of the seasons and solar activity conditions, a dominant fraction of MSTIDs propagate equatorward with velocity in the range of 50 – 150 m s^-1 and period in the range of 30 – 60 minutes. Their occurrence shows seasonal and solar activity dependency. They normally occur during winter and equinoctial months. During solar maximum conditions, the occurrence was comparatively higher (~72 %) than during solar minimum years (below 50 %). Furthermore, the MSTIDs’ occurrence showed a dependence on IMF Bz, being generally higher during intervals of prolonged northward or southward IMF Bz, and lower during small or fluctuating IMF Bz conditions. Our results indicate that MSTIDs occurrence showed seasonal variation as well as dependence on the solar forcing over the EISCAT-3D location. Therefore, this statistical study will help in providing comprehensive insight about the MSTIDs which will be effective in scheduling future experimental runs of EISCAT-3D to explore their 3-dimensional structures.