Turbulence around the turbopause deduced from ionospheric sporadic E for MAP

The turbulent diffusivity around the turbopause is deduced from the parameters of ionospheric sporadic E /Es/ and atmospheric models assuming the validity of the wind-shear theory of midlatitude sporadic E. It has been found that during circulation disturbances in the lower thermosphere connected with stratospheric warmings the turbulent diffusivity appears to decrease. The results obtained so far indicate that the characteristic events of the winter months are shown not only by the large scale dynamics in the lower thermosphere, but also by the small scale phenomena and thus the turbulent diffusivity could contribute to the development of the winter anomaly. 15 references