Investigation of seasonal and diurnal cycles on the height dependence of optical turbulence in the lower atmospheric boundary layer

Analysis of wave propagation in the visible and near infrared (IR) has to take into account the influence of optical turbulence due to variations of temperature. Especially the operation area of most electro-optical systems in the lower atmospheric boundary layer is affected by atmospheric turbulence. The influence of thermal and mechanical turbulence on the height dependency of the structure function parameter of the refractive index Cn² is investigated. Cn² is used for the characterization of optical turbulence. The main focus is set on seasonal and diurnal variations. Variations dependent on atmospheric stability in the surface layer are analysed. Results are presented from the long-term experiment VerTurM (Vertical Turbulence Measurements). The experiment is continuously performed since June 2009 in rural country at north-western Germany. The vertical structure of optical turbulence is explored using three different measurement techniques to cover the altitude range between the surface and about 400 m height. Model comparisons are carried out and discussed.