A study of the dynamic regime of the middle atmosphere in the 2014–2015 winter season was carried out using reanalysis data. The variability of the atmosphere as a whole this winter was due to the development of sudden stratospheric warming (SSW). Despite the fact that this SSW is classified as minor, it has had a significant impact on the temperature regime, circulation and chemical composition of the middle atmosphere. The main attention is paid to the study of wave activity variations of stationary planetary waves (SPW) and processes caused by wave activity before, during and after the SSW, as well as the sensitivity of upper-tropospheric jet streams (JS) to stratospheric and mesospheric processes. The method of perturbed potential enstrophy analysis is used to study wave activity and wave processes. It is shown that variations in wave activity before the development of the SSW are due to wave-wave interactions, and during and after are due to the exchange processes of SPW2 (zonal wave number 2) with the mean flow. The development of the minor SSW in January 2015 had similar characteristics to the development of the major SSW, which likely led to the observed differences in the distribution of JS frequency during the month before and after the SSW. The highest JS frequency after the SSW was noted at more southern latitudes compared to the period before the SSW across most of the North Atlantic region. It has been shown that the greatest changes in JS frequency are associated with the southward shift of the upper-level frontal zone, which is in turn triggered by the deepening of upper-level troughs due to the intrusion of cold stratospheric air into the upper troposphere.
K. A. Didenko (Wed,) studied this question.