Some Results of Remote Sensing of Atmospheric Refractivity Near the Ground Using Laser Beam Scintillations

Abstract

An experimental set-up developed for the measurement of path-averaged atmospheric refractive index structure parameter (C²_n) is described followed by a brief summary of the theory involved in the generation and amplification of refractive index inhomogeneities. The results of the experiments conducted in the surface layer using a Helium-Neon laser source over an optical path length of 61.5 m at a height of 1.1 m above uniform surface are presented. The observed C²_n ranges from 0.97 × 10⁻¹² to 1.3 × 10⁻¹⁴ m^−2/3. The diurnal variation of C²_n shows rapid increase during morning hours, peaking around noon and slow decrease during evening hours. The observed relationship between the variations of C²_n and temperature is explained and further studies to support and extend the present findings are indicated.

Indexing terms:

• Remote sensing
• Laser scintillations
• Refractive index
• Atmospheric turbulence
• Temperature range