Numerical Modeling of the Global Circulation of the Earth's Middle Atmosphere for Different External Conditions

Results of numerical modeling of global distributions of the horizontal and vertical wind in the Earth's
middle atmosphere are presented and discussed. For obtaining the presented simulation results, the
mathematical model of the global neutral wind system of the Earth’s atmosphere, developed earlier in
the Polar Geophysical Institute, was applied. The peculiarity of the utilized model consists in that the
internal energy equation for the neutral gas is not solved in the model calculations. Instead, the global
temperature field is assumed to be a given distribution, i.e. the input parameter of the model.
Moreover, in the model calculations, not only the horizontal components but also the vertical
component of the neutral wind velocity is obtained by means of a numerical solution of a generalized
Navier-Stokes equation for compressible gas, so the applied mathematical model is non-hydrostatic.
The utilized model enables to calculate three-dimensional global distributions of the zonal, meridional,
and vertical components of the neutral wind at levels of the troposphere, stratosphere, mesosphere,
and lower thermosphere. In the present work the mathematical model is applied for investigation of
the influence of horizontal non-uniformity of the neutral gas temperature on the formation of the
Earth's atmosphere circulation for conditions corresponding to four different seasons (winter, spring,
summer, and autumn). Also, the mathematical model is applied for investigation of the influence of
solar activity on the formation of the large-scale global circulation of the Earth's atmosphere. The
results of simulation indicate that the horizontal non-uniformity of the neutral gas temperature, which
is distinct in different seasons, ought to considerably influence the formation of the global neutral wind
system in the middle atmosphere, in particular, the large-scale circumpolar vortices of the northern
and southern hemispheres. Also, the simulation results indicate that solar activity ought to influence
considerably on the formation of global neutral wind system in the mesosphere and lower
thermosphere. The influence is conditioned by the vertical transport of air from the lower
thermosphere to the mesosphere