Scintillations of centimeter waves and the atmospheric irregularities from radio occultation data

Abstract

[1] The analysis of field strength fluctuations of radio waves in the wavelength band l = 2 cm of radio occultation measurements between orbital station MIR and a geostationary satellite is presented. Examples of field strength E dependences on altitude H 0 of the ray path are given. We find two types of fluctuations connected to turbulence and stratified formations in the atmosphere. The RMS deviations of field strength are investigated as function H 0 for both types. The frequency spectra of the field strength scintillation G(F ) are analyzed to determine a spectral index n and characteristic frequency of fluctuations F 0 for different minimum altitudes of the ray path H 0 . It is shown that the troposphere at H 0 < 7 km in the high-frequency part of the spectrum is described by a function G(F ) $ F Àn , where the spectral index n on average is equal to 2.5, which corresponds to the theoretical value for the Kolmogorov spatial spectrum. In the stratosphere at H 0 = 15-35 km the mean value n equals 3.6, and only in 13% of the cases there are spectra that are in agreement with the Kolmogorov law. At the basis of the analysis of the connection between the spatial spectrum of the refractive index fluctuations and the frequency spectrum of field strength fluctuations, we discuss the application of the radio occultation technique for investigation of the atmospheric inhomogeneities.INDEX TERMS: 6904 Radio Science: Atmospheric propagation; 6994 Radio Science: Instruments and techniques; 0659 Electromagnetics: Random media and rough surfaces; KEYWORDS: radio occultation, atmosphere, wave, scintillation Citation: Yakovlev, O. I., S. S. Matyugov, and V. A. Anufriev, Scintillations of centimeter waves and the atmospheric irregularities from radio occultation data,

Fluctuations of radio occultation signals in X/K band in the presence of anisotropic turbulence and differential transmission retrieval performance

“…We adopted the turbulence to be characterized by an external scale 2 π /κ ext = 100 m, internal scale 2 π /κ int = 15 m, exponent μ = −4 for the 2D spectrum (corresponding to exponent μ 3 D = −5 for the 3D spectrum) that follows [ Gurvich and Chunchuzov , 2003, 2005]. Yakovlev et al [2003] obtained a close value of μ 3 D = 4.5.…”

“…The outer scale typically lies around 50–150 m. The internal scale is chosen close to the diffractive limit [ Gorbunov et al , 2004]: h ≥ , which is about 20 m. The effect of adding smaller scales into the amplitude scintillation will be very small due to both the decrease of spectral density of turbulence and diffraction. According to experimental studies [ Kan et al , 2002; Yakovlev et al , 1995, 2003], the scales 30–50 m provide about 1% of the total scintillation power. The contribution of the scales below 30 m is accordingly still smaller.…”

“…However, a smaller anisotropy results in a smaller scintillation power, therefore, in the latter case our anisotropic model will overestimate scintillations. Our turbulence model results in a realistic pattern of scintillations of the simulated signals looking similar to the experimentally observed ones [Kan et al, 2002;Yakovlev et al, 1995Yakovlev et al, , 2003].…”

Radiowave fluctuations in the polar ionosphere on the satellite-to-satellite paths under high solar activity

“…The high accuracy of measurements of signal amplitudes and phases in radio-occultation experiments also made it possible to obtain information on fluctuations of radio waves and small-scale atmospheric [2,6,7] and ionospheric [8,9] irregularities. Earlier, as a result of multiyear studies, ionospheric fluctuations of radio waves on the satellite-ground-based reception site paths were studied in detail.…”

“…The first series of such experiments was run in Russia in 1990-1998 using the orbital station "Mir" and geostationary satellites [1,2]. The second cycle of radio-occultation studies was performed in the USA in 1995-1998 using the satellite "Microlab" that received signals from the navigational GPS satellites [3].…”