Coupling between parameters of Es layer and planetary waves during SSW 2008, 2010

We report the features of the critical frequency foEs and probability of the sporadic E layer occurrence P(Es) estimated at the Kaliningrad ionosonde station (54°N, 20°E) during the sudden stratosphere warming (SSW) in winter during the years 2008 and 2010. Additionally we use the neutral atmosphere (temperature, wind circulation data at 10 hPa) data for the same temporal interval. Considered periods were characterized by the low solar and geomagnetic activities. We investigate the indirect relation of the neutral temperature in the stratosphere with the long-term variability in ionospheric Es layer parameters during SSW. We found a rather good correlation between the Es layer parameters and the stratospheric temperature increase during the SSW events. We used the continuous wavelet transforms in order to demonstrate the relationship between planetary wave (PW) activity and temporal variability of the sporadic E-layer parameters during SSW 2008 and SSW 2010. We detect a significant wave-like oscillation with periods covering a planetary oscillation in both Es layer parameters. Generally, the oscillations were observed in two bands that corresponded to the periods of 8–10 days before SSW and 12–16 and more days’ band during SSW.