Frequency characteristics of the troposphere and ionosphere variations in periods of solar terminator passage

An analysis of the results of lidar observations in the lower atmosphere and observations of the total electron content in the ionosphere (TEC) in Kaliningrad (53°N, 22°E) during the period of solar terminator passage is presented. The observations at troposphere altitudes were performed with a two-wavelength atmospheric lidar (532 and 1064 nm). The ionospheric TEC was determined using signals from GLO-NASS navigation satellites. The observations in the lower atmosphere were performed in February and March 2012, starting ～1 h before sunrise and ending ～1–2 h after sunrise, whereas ionospheric observations were performed continuously throughout the day. Analysis of the spectrum of the observed parameters showed that, during solar terminator passage, the lower atmosphere and ionosphere parameters vary with periods of 4–6 min. Variations of the parameters in the atmosphere with these periods are associated with the propagation of acoustic-gravity waves (AGW). Analysis of the experimental results shows that AGW arise in the lower atmosphere and propagate vertically to ionospheric altitudes. It is assumed that AGW with these periods can be efficiently excited in the lower atmosphere and play an important role in the dynamic interactions between the lower and upper atmosphere.