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Study of Atmospheric Refractive Index Structure Constant over India using Radiosonde Measurements

An application of Kolmogorov Theory to estimate atmospheric turbulence in optical and near-infrared domain

by Pranoy Ghosh (Author) Arijit De (Author)

Research Paper (undergraduate) 2018 13 Pages

Physics - Other

Summary

Why should we study atmospheric refractive index structure constant? Atmospheric refractive index structure constant is a quantitative measurement of turbulence induced fluctuations in refractive index parameter for visible and near-infrared wavelength. Atmospheric turbulence has strong impact on astronomical imaging, aerial surveying, terrestrial geodesy, optical ranging, and wireless optical communication. Major effects of turbulence are beam broadening, irradiance fluctuations (scintillation), and angle of arrival fluctuations. Hence an estimate of turbulence that may prevail at a site seasonally is helpful. Also Modulation Transfer Function of the atmosphere is measurable by refractive index structure constant. Fried parameter which is a measure of astronomical seeing, can be calculated from structure constant's vertical profile. Good image quality requires structure constant being as small as possible. Our interest in studying structure constant profiles is further enhanced by recent published work claiming that daily variations in mean structure constant values may serve as Earthquake precursor.

In this work, Atmospheric refractive index structure constant has been studied for five different stations over India using radiosonde measurements. The monthly variations of structure constant have been observed with lower heights studied separately. Vertical profiles of structure constant have been investigated. Linear correlation between structure constant and humidity has been found to exist. During correlation studies Type-1 error probability p value patterns were generated. P value patterns were found to be systematic.

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Title: Study of Atmospheric Refractive Index Structure Constant over India using Radiosonde Measurements