A discussion on D and E region winds over Europe - Large-scale motion in the upper stratosphere and mesosphere: an evaluation of data and theories

Abstract

Between heights of 25 and 100 km, fluid motion is responsible for carrying energy from the radiative heat source near the summer pole to the radiative heat sink near the winter pole. The way this transfer is organized will form the theme of this contribution. All scales of motion are important: (1) The zonal-mean motion contains most of the kinetic energy but contributes to the energy transfer only through a comparatively weak circulation in the meridional plane. (2) Stationary large-scale eddies are prominent at least in the winter and carry a considerable fraction of the energy transfer. (3) Transient large-scale eddies of a variety of types are evident in the data but are likely to be feeble transporters of energy. (4) Gravity-inertial waves, generated by tidal forcing and orography and representing some aspects of small-scale turbulence, are associated mainly with the vertical transfer of energy.