Small-scale variations of radio refractive index in the troposphere. Part 2: Spectral characteristics

Spatial (wave-number) spectra of refractive-index variations have been derived from measurements of frequency spectra made with a spaced-cavity refractometer located in and near elevated inversion layers. The intensity of the 1-dimensional wave-number spectrum decreased with increasing wave number k as k¿n, with values of n generally greater than 5/3 and occasionally as large as 3 [k may be regarded as equal to 2¿/(blob size)]. The largest values of n were usually found in layers across which the value of Richardson´s number was appreciably greater than unity. The variation from sample to sample in any sounding in the spectra intensity at k ¿ 100m¿1 was often appreciably less than the corresponding variation at k ¿ 1m¿1. The results illustrate the dependence of spectral characteristics on sampling time.