Structure function C(2)(n) profiling by two-color stellar scintillation with atmospheric dispersion

Two-color single-star scintillation cross-correlation functions are estimated involving the use of two wavelength filters centered on 409 and 800 nm. From these estimations and using the atmospheric dispersion theory already proposed by Hudgin, turbulent layer heights are measured. Then, vertical C(2)(n)Deltah profiles are obtained every 2 min 45 sec using the slowly decreasing elevation of Sirius. The coherence with another method proves its interest. Furthermore, when the zenith angle of the observed star exceeds ~70 degrees , turbulence heights smaller than 800 m (otherwise unattainable with stellar scintillation measurements) can be detected with a vertical resolution of 300 m.

Outer scale of turbulence appropriate to modeling refractive-index structure profiles

The outer scale of turbulence L (0) has been calculated from values of the refractive-index structure coefficient C(2)(N) obtained from spatio-angular correlation measurements of stellar scintillation. It is found that L(0) </= 5 m for a large range of observations in France, U.S.A., and Chile and that its dependence on altitude Z follows the same general form at all these sites. The prediction of C(2)(N)(Z) profiles is shown to be feasible utilizing standard meteorological radiosonde data and this L(0)(Z) curve. A simple model based on dimensional analysis and a more complicated stochastic model are compared, but the latter appears to have no advantage.

Wind and C(2)(N) profiling by single-star scintillation analysis

The spatiotemporal cross-correlation function of single-star scintillation is estimated. From this estimation and using a priori knowledge of the theoretical shape of the correlation peaks, a method for simultaneously measuring horizontal velocity, altitude, and integrated C(2)(N) value for each atmospheric turbulent layer between 2 and 20 km is described. Taylor's hypothesis is tested for one particular layer and the lifetime of certain turbulent eddies is estimated. Results are in good agreement with two other methods.