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The main features of upper atmosphere dynamics as an important part of upper atmosphere climatology are presented. The dynamics of the mesosphere and lower thermosphere (MLT) are of special interest. The results are based on the long series of investigations in East Siberia and data from a world-wide network of observatories. We present the regional climatic norms for the prevailing wind and semi-diurnal tide and the main features of the quasi-periodic structure of the wind field. The non-zonality of MLT dynamics is demonstrated as well as regional differences in the response of the wind field to stratospheric disturbances, solar activity variations and geomagnetic storms.

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A large body of experimental evidence lends credit to the existence of a close relationship between ionospheric parameters and the underlying atmosphere. Vertical-incidence ionospheric sounding data and temperature measurements at stratospheric (30 km) and mesospheric (80 km) heights have been used in investigating the interrelation between the occurrence of fluctuations with periods of planetary waves in temperature variations at different heights and inF2layer critical frequency variations (foF2) under low solar activity conditions for the time interval 2006-2007. The distinctive characteristics of the manifestation of common periodicities of the wave structures under consideration are discussed. The statistically significant periods of stratospheric and mesospheric temperature fluctuations vary from 11 to 49 days, whereas foF2 periodograms show higher-frequency fluctuations with periods of 5, 8, 9, and 10 days. The study revealed a similarity between periodic structures for the variations in the parameters involved.