Solar Scintillometry: Calibration of Signals and its Use for Seeing Measurements

Abstract

Since 1993 it is known that there is a good correlation between the scintillation in the solar irradiance and solar image quality (Seykora, 1993). This effect is now being used in a number of experiments to evaluate solar image quality and to measure site seeing. In this paper we explore further the calibration of this scintillation (_σI) in terms of the Fried parameter (_r0) taking into account variations in the refractive index structure constant C ²_N with height (h), zenith distance (ζ) dependence and the effects of wind velocities. A variant in the scintillometer setup is proposed which decreases sharply the dependance on C ²_N , ζ, and the wind velocities. It uses an array of scintillometers. The same array can be used to measure theC ²_N profile with height. Some preliminary results of the calibration of current NSO site survey measurements are presented.