SEASONAL AND LATITUDINAL VARIATIONS OF EDDY DIFFUSION-COEFFICIENT IN THE MESOSPHERE AND LOWER THERMOSPHERE

Two approaches to turbulence parameter determination around the turbopause are discussed. It is shown that there is a contradiction in the results concerning seasonal variations of the eddy diffusion coefficient between direct measurements and estimations based on minor constituents. Taking account of the vertical mean transport in the continuity equations for the above constituents might eliminate that contradiction. Results of the re-examination of the authors' data on the Ar to N2 ratio published earlier are presented. The results show stronger turbulence in winter than in summer, the amplitude of the effect increasing towards higher latitudes.