Abstract
Different experimental methods are available for the measurement of atmospheric refractive index structure constant (Cn2), which is an index of atmospheric turbulence to be known prior to an accurate estimation of any atmospheric quantity using remote sensing techniques. An experimental setup that combines an optical scientillometer and two separate differential micro thermometers for determining atmospheric Cn2 has been developed at the Indian Institute of Tropical Meteorology (IITM), Pune, India. The results of the experiments performed during the months of April, November and December 1991 are discussed. The temporal variations in Cn2 measured simultaneously from both optical and thermal techniques showed correspondence and correlated by a scale factor, Cn(optical) = Cn (thermal)×0.89+6.45×10-7m-1/3. The order of Cn2 was found to vary from 10-15 to 10-12 m10-2/3 exhibiting maximum value during afternoon hours and minimum during the periods fo just after sunrise and sunset. The details of the experiment and performance of the techniques are presented. The variations in Cn2 observed from both methods are explained in relation to thermal stratification of the atmosphere.
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Pandithurai, G., Sharma, S., Raj, P.E. et al. Optical-Thermal Determination Of Cn2 in the Lower Atmosphere. J Opt 22, 68–72 (1993). https://doi.org/10.1007/BF03549251
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DOI: https://doi.org/10.1007/BF03549251