Effect of variations in short wave solar radiation on atmosphere composition and dynamics according to observations and modeling

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   Short wave solar radiation flux at the top of the Earth's atmosphere
   undergoes variations within a broad range of time scales. Among them are
   the oscillations with periods of about 11 years (11-year cycle), 2-2.5
   years (quasi-biennial cycle), and 27 days (27-day or rotational cycle).
   The amplitude of the 27-day cycle may approach 60% of the amplitude of the
   11-year cycle, while the quasi-biennial variations of the solar radiation
   flux are several times weaker. In this report, we present the results,
   concerning some effects of the three solar cycles on the Earth's middle
   atmosphere.
  

   The effect of the 27-day solar cycle on the atmosphere was studied by the
   HAMMONIA chemistry climate model. While the thermal and chemical responses
   are very distinct and permanent in the upper atmosphere under a constant
   forcing, the responses in the stratosphere and mesosphere have
   intermittent character and vary considerably in time. In the extratropics
   the responses are, in general, seasonally dependent with frequently
   stronger sensitivities in winter than in summer. The model results show,
   that dynamical processes may play an important role in the stratospheric
   response to the 27-day solar cycle.
  

   The most important component of the atmospheric circulation is the
   quasi-biennial oscillations in zonal velocity of equatorial stratospheric
   wind, which affect considerably the dynamics of the atmosphere in the
   middle and polar latitudes. We found a high coherence of quasi-biennial
   oscillations in stratospheric wind velocity with similar variations in
   short wave solar radiation. The oscillations in wind velocity near the
   stratopause layer are in phase with the quasi-biennial solar variations.
   We show, that the meridional gradient of ozone concentration in this layer
   undergoes quasi-biennial variations which, according to the thermal wind
   equation, could bring about the synchronization of quasi-biennial
   oscillations in the wind velocity with solar variations.
  

   Using the measurement data, we found the effect of the 11-year cycle in
   solar activity on stratospheric nitrogen dioxide in the middle and polar
   latitudes. It is opposite in sign to the effect of the 11-year cycle on
   stratospheric ozone. Analysis of observational data and model calculations
   show, that the 11-year solar cycle affect significantly the meridional
   transport of stratospheric ozone in winter time, especially in the
   northern hemisphere. We also found an 11-year cycle in the velocity of the
   equatorial stratospheric wind. The vertical profile of the phase of the
   11-year oscillations in wind velocity is similar to the profile of the
   phase of quasi-biennial oscillations. Additionally, we revealed an 11-year
   modulation of the period and amplitude of quasi-biennial oscillations in
   wind velocity themselves.