A previously presented method for modeling Kolmogorov phase fluctuations over a finite aperture is both formalized and improved on. The method relies on forming an initial low-resolution Kolmogorov phase screen from direct factorization of a covariance. The resolution of the screen is then increased by a randomized interpolation to produce a Kolmogorov phase screen of the desired size. The computational requirement is asymptotically proportional to the number of points in the phase screen.

The measurement of the strength of atmospheric optical turbulence by use of a modified generalized SCIDAR (scintillation detection and ranging) inversion technique is outlined and demonstrated. This new method for normalizing and inverting scintillation covariances incorporates the geometry specific to generalized SCIDAR. Examples of profiles from two astronomical observation sites are presented.

We propose a technique for the accurate modeling and simulation of scintillation patterns that are due to Kolmogorov statistics without assuming periodic boundary conditions. We show how the more physically justifiable assumption of smoothness results in a propagation kernel of finite extent. This allows the phase screen dimensions for an accurate simulation to be determined, and truncation can then be used to eliminate the unwanted spectral leakage and diffraction effects usually inherent in the use of finite apertures. A detailed outline of the proposed technique and comparison of simulations with analytic results are presented.

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The strength of optical turbulence, Cn2(z), 2-3 m above ground level, was measured as a function of distance along a 1.23-km path by the simultaneous capture of the scintillation from two infrared laser sources. The data collected differ in a number of important aspects from the normal vertical scintillation detection and ranging (SCIDAR) data in astronomy. The SCIDAR inversion method for the horizontal path problem is outlined and demonstrated on experimental data collected from three field trials.

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SCIDAR (SCIntillation Detection And Ranging) has been used at various sites around the world to characterise turbulence strength. However little focus has been given to finding average wind velocity, V (h), from SCIDAR data. Current methods rely on the detection of full spatio-temporal covariance profiles, containing a triplet pattern associated with each turbulent layer present. A new technique for finding V (h) from noisy scintillation covariance images using a modified CLEAN algorithm has been developed to handle partial spatio-temporal covariance profiles. The application of the new algorithm to data collected from Mount John University Observatory is demonstrated.

Site measurements were collected at Mount John University Observatory in 2005 and 2007 using a purpose-built scintillation detection and ranging system. C N 2 (h) profiling indicates a weak layer located at 12-14 km above sea level and strong low altitude turbulence extending up to 5 km. During calm weather conditions, an additional layer was detected at 6-8 km above sea level. V(h) profiling suggests that tropopause layer velocities are nominally 12-30 m s À1 , and near-ground velocities range between 2 and 20 m s À1 , dependent on weather. Little seasonal variation was detected in either C N 2 (h) and V(h) profiles. The average coherence length, r 0 , was found to be 7 AE 1 cm for the full profile at a wavelength of 589 nm. The average isoplanatic angle, y 0 , was 1.0 AE 0.1 arcsec. The mean turbulence altitude, h 0 , was found to be 2.0 AE 0.7 km above sea level. No average in the Greenwood frequency, f G , could be established due to the gaps present in the V(h) profiles obtained. A modified Hufnagel-Valley model was developed to describe the C N 2 (h) profiles at Mount John, which estimates r 0 at 6 cm and y 0 at 0.9 arcsec. A series of V(h) models were developed, based on the Greenwood wind model with an additional peak located at low altitudes. Using the C N 2 (h) model and the suggested V(h) model for moderate ground wind speeds, f G is estimated at 79 Hz.