干旱区生态环境知识资源中心

New results of the (temperature) refractive index structure parameter (C-T(2)), C-n(2) are presented from fast response sensor observations near the ground and also using a kite/tethered blimp platform and an aircraft, at the Edward Air Force Base in Mojave Desert, California. Additional optical measurements include near-ground scintillation observations over horizontal paths. Atmospheric turbidity were also calculated from direct beam solar radiation measurements using pyrheliometer. Comparisons were made of the observed profiles of refractive index structure parameters (C-n(2)) with theoretical modeled profiles, and two derived quantities such as transverse coherence length (r(0)) and isoplanatic angle (theta(0)) for a slant path are discussed. All of these parameters are the major indicators of turbulence and are important to design an aircraft or space-craft-based free-space laser communication and high resolution optical synthetic-aperture imaging systems. Non-isotropic turbulence observations from some of the data will be pointed out. Probability density functions (PDF) of the distribution of C-n(2) Will be described using histograms. Fundamental limits imposed by atmospheric effects in high data rate communication and optical synthetic-aperture imaging systems will be discussed.