The atmosphere of mars analyzed by integral inversion of the Mariner IV occultation data

Fjeldbo, G.; Eshleman, V. R.

doi:10.1016/0032-0633(68)90020-2

Cited by 179 publications

(95 citation statements)

References 13 publications

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“…[9] The data were analyzed using the method of integral inversion [Fjeldbo and Eshleman, 1968;Kliore, 1972] to obtain a vertical profile of the refractivity from the refractive bending angle determined by the Doppler residuals and the ephemeris of the spacecraft relative to Callisto. The refractivity is defined as:…”

Section: Data Analysis and Resultsmentioning

confidence: 99%

Ionosphere of Callisto from Galileo radio occultation observations

et al. 2002

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[1] An ionosphere has been detected at Callisto by the Galileo spacecraft, using the radio occultation technique. There were four usable occultations by Callisto, providing eight observation opportunities, all equatorial and near the terminator (entry and exit observations). Detectable electron densities were obtained from six of the eight opportunities. It was found that a detectable ionosphere was only present at the observed location when the trailing hemisphere of Callisto, which is the one that is impacted by the corotating plasma of Jupiter's magnetosphere, was illuminated by the Sun. Two of these observations yielded well-defined electron density profiles, having peak densities of 15,300 and 17,400 cm À3 at altitudes of 27.2 and 47.6 km and topside plasma scale heights of 29.6 and 49.0 km. Four different methods, based on both photoionization and electron impact ionization, were used to obtain estimates of the corresponding neutral densities at the surface. The various assumptions inherent in these methods required using a variety of parameters, (cross sections, rate constants, etc.) all with their associated uncertainties. It was rather surprising and reassuring to find that all of the methods used to estimate the surface neutral density gave very similar results in each of the eight cases.The estimated values fall between 1 and 3 Â 10 10 cm À3 , leading to an estimate for the column density of from 3 to 4 Â 10 16 cm À2 .

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Section: Data Analysis and Resultsmentioning

confidence: 99%

Ionosphere of Callisto from Galileo radio occultation observations

et al. 2002

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“…Since then, occultafion techniques have been used to infer precious information about the internal structure, composition, and density profiles of constituents of the atmosphere [Robie and Hays, 1972]. These techniques, which associate sources such as the Sun, stars, or artificial satellites to a ground-based or spaceborne receiver, have enabled sounding of Earth's atmosphere [Rangaswamy, 1976;Kursinski et al, 1996] as well as those of remote planets [Fjeldbo and Von Eshelman, 1968;Fjeldbo et al, 1971;Lindal et al, 1983Lindal et al, , 1987. Modern technology has contributed a great deal to improving the vertical resolution of the retrieved data by yielding better accuracy of the position and velocity components of the satellites involved in the occultafion and by allowing the possibility of increasing the sampling rates as well as reducing receiver noise to acceptable levels.…”

Section: Introductionmentioning

confidence: 99%

Effect of periodic horizontal gradients on the retrieval of atmospheric profiles from occultation measurements

Belloul¹,

Hauchecorne²

1997

Radio Science

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Abstract. Spherical symmetry is generally assumed during the retrieval process of atmospheric prof'des from occultation measurements. The existence of periodic horizontal gradients, occurring on scales comparable to the distances traveled by the rays around their tangent point, is produced by gravity waves. These waves can introduce density perturbations of up to 1 or 2 % in amplitude and affect the retrieved parameters accordingly. We show the consequences of ignoring these gradients in the retrieved refractivity profiles when spherical symmetry is assumed. We f'md that only the waves, with horizontal wavelengths close to the horizontal distance that rays travel in their f'mal 6 or 8 km in the vertical before they are tangent in the atmosphere, will have an influence on the retrieved profiles by introducing a phase delay in the local prof'de of the retrieved refractivity. The horizontal wavelength of these waves corresponds to the minimum horizontal resolution associated with the retrieved profiles. We also find that smaller scale waves do not have any significant impact on the retrieved prof'des, as their contribution cancels out by averaging through the periodic perturbation, while waves with very long horizontal wavelengths are in good agreement with a local spherical symmetry assumption.

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“…On the assumption that the neutral atmosphere is well mixed, we adopt a constant V of 1.81×10 −17 m 3 based on the composition of 96.5% CO 2 and 3.5% N 2 using the constants given in Fjeldbo and Eshleman (1968). The neutral and ionospheric contributions are separated in altitude with the boundary around 100 km altitude (see results of Pätzold et al, 2007a).…”

Section: Derivation Of Atmospheric Density and Temperaturementioning

confidence: 99%

Radio occultation experiment of the Venus atmosphere and ionosphere with the Venus orbiter Akatsuki

et al. 2011

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The Radio Science experiment (RS) in the Akatsuki mission of JAXA aims to determine the vertical structure of the Venus atmosphere, thereby complementing the imaging observations by onboard instruments. The physical quantities to be retrieved are the vertical distributions of the atmospheric temperature, the electron density, the H 2 SO 4 vapor density, and small-scale density fluctuations. The uniqueness of Akatsuki RS as compared to the previous radio occultation experiments at Venus is that low latitudes can be probed many times thanks to the nearequatorial orbit. Systematic sampling in the equatorial region provides an opportunity to observe the propagation of planetary-scale waves that might contribute to the maintenance of the super-rotation via eddy momentum transport. Covering the subsolar region is essential to the understanding of cloud dynamics. Frequent sampling in the subsolar electron density also helps the understanding of ionosphere dynamics. Another unique feature of Akatsuki RS is quasi-simultaneous observations with multi-band cameras dedicated to meteorological study; the locations probed by RS are observed by the cameras a short time before or after the occultations. An ultra-stable oscillator provides a stable reference frequency which is needed to generate the X-band downlink signal used for RS.

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The atmosphere of mars analyzed by integral inversion of the Mariner IV occultation data

Cited by 179 publications

References 13 publications

Ionosphere of Callisto from Galileo radio occultation observations

Ionosphere of Callisto from Galileo radio occultation observations

Effect of periodic horizontal gradients on the retrieval of atmospheric profiles from occultation measurements

Radio occultation experiment of the Venus atmosphere and ionosphere with the Venus orbiter Akatsuki

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