Model for estimating the refractivity structure constant in intermittent clear air

We explain discrepancies in comparing estimations of the refractive-index structure constant Cn2 in clear air by means of different techniques by taking into account atmospheric intermittency effects. We formulate a model of C,2 in intermittent turbulence on the basis of the Tatarskii theory, and we calculate the mean value of Cn2 through a probabilistic approach. We deduce a factor, which gives a measure of the statistical reduction of turbulence that is due to intermittency, within the model framework. A procedure for estimating the mean value of Cn2 from data of a specific radiosonde observation is illustrated