High-resolution VHF radar observations of turbulence structures in the mesosphere

Abstract

Results from a study of mesospheric turbulence, using a VHF radar with a height resolution of 150 m, are presented. Three types of turbulence structures have been identified: blobs, sheets and layers. Blobs and sheets occurred sporadically, predominahtly at heights of 60-70 km. Above 70 km, layers thicker than 1 km were dominant, which were advected with the background wind. Velocity fluctuations in these structures were proportional to their thickness. The role of partial or Fresnel reflections is discussed and possibility of diffuse reflections below 70 km is noted. Problems in estimating transport coefficients from radar data are outlined.