Studying effects of winter sudden stratospheric warmings from observations at middle and high latitudes

We present the results of a comparative analysis of disturbances in the upper atmosphere during the winter sudden stratospheric warmings (SSWs) of various types in January 2013 and February-March 2016 from observations at middle and high latitudes. To investigate the upper mesosphere and low thermosphere (MLT) signatures of the SSWs, we used experimental data on the rotational temperature of the hydroxyl molecule (OH (6-2)) obtained from spectrometric measurements at the Geophysical Observatory of ISTP SB RAS (51.8 degrees N, 103.1 degrees E, Tory). To study the ionospheric disturbances, we analyzed the data on the peak electron density NmF2 obtained from the Irkutsk (52.3 degrees N, 104.3 degrees E) and Norilsk (69.2 degrees N, 88.0 degrees E) DPS-4 Digisondes. The most significant effect of the 2013 January SSW in the MLT was in an increase in the day-to-day variability of the mesopause temperature, due to the intensification of planetary wave activity at these altitudes. During the 2016 February and 2016 March SSWs, the greatest effects were in an increase in the diurnal variability of the mesopause temperature, which can be caused by the influence of tides and internal gravity waves. We revealed strong infra-diurnal NmF2 disturbances over Irkutsk and Norilsk during the 2013 January and 2016 February SSWs. For the February 2016 SSW, the disturbances had a tidal structure. For the 2013 SSW, we found violation of correlation between the variations in NmF2 and solar activity that can be caused by an intensification of the planetary wave activity at the ionospheric heights.