A comparison between estimations of Fried's parameter r o simultaneously obtained by measurements of solar granulation contrast and of the variance of angle-of-arrival fluctuations

Estimations of Fried's parameter r _o are performed simultaneously using the same telescope, from the observed solar granulation contrast and from the variance of angle-of-arrival fluctuations. The results are well correlated and the mean ratio between the values for r _o obtained from the 2 methods is found to be equal to 1.4.The sensitivity and accuracy of the methods are discussed in terms of their range of application (site testing, seeing measurements during solar observations ...). Temporal power spectra of turbulent energy are computed and evidence of long period oscillations of about 10 min is found.