Lunar Tide in Ionospheric Peak Electron Density and Its Interannual Variability

Lunar tide is an effective agent for the vertical coupling of atmosphere ionosphere system. It is a ubiquitous phenomenon observed in various ionospheric parameters. Interannual variability of lunar tide in ionosphere is linked to the dynamics of the middle and upper atmosphere. We present a new method for the estimation of lunar tide from ground-based ionosonde observations. Long term observations from 40+ ionosonde stations is used for the estimation of lunar tide in peak electron density. Estimated lunar tide amplitude shows strong seasonal variation and can reach as much as 20% of the background electron density in winter. Interannual variability of lunar tide and its connection to atmospheric processes is explored.