Structure of Saturn's Mesosphere from the 28 Sgr Occultations

Hubbard, W. B.; Porco, C. C.; Hunten, D. M.; Rieke, G. H.; Rieke, M. J.; McCarthy, Donald W.; Haemmerle, V.; Haller, Joseph W.; McLeod, B. A.; Lebofsky, L. A.; Marcialis, R. L.; Holberg, J. B.; Landau, R.; Carrasco, L.; Elias, J. H.; Buie, M. W.; Dunham, E. W.; Persson, S. E.; Boroson, Todd A.; West, S. C.; French, R. G.; Harrington, J.; Elliot, J. L.; Forrest, W. J.; Pipher, J. L.; Stover, R. J.; Brahic, A.; Grenier, I. A.

doi:10.1006/icar.1997.5839

Cited by 46 publications

(84 citation statements)

References 18 publications

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“…If similar asymmetric structures are present in the middle atmosphere, these velocities are more than adequate to provide the necessary magnetospheric perturbations. At Saturn, Hubbard et al (1997) showed that equatorial winds of ∼450 m/s persisted into the mesosphere region, and we would expect these winds to exhibit some asymmetries analagous to those observed in the lower atmosphere.…”

Section: Conductivities and Wind Speedsmentioning

confidence: 84%

Periodic modulation of gas giant magnetospheres by the neutral upper atmosphere

Smith

2006

Ann. Geophys.

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Abstract. Periodic signatures present in the magnetospheres of both Jupiter and Saturn have yet to be fully explained. At Jupiter the unexplained signatures are related to emissions from the Io torus ("System IV"); at Saturn they are observed in emissions of kilometric radiation (SKR) and in magnetometer data. These signatures are often interpreted in terms of magnetic field anomalies. This paper describes an alternative mechanism by which the neutral atmosphere may impose such periodic signatures on the magnetosphere. The mechanism invokes a persistent zonal asymmetry in the neutral wind field that rotates with the planet. This asymmetry must be coupled to substantial ionospheric conductivity. It is then able to drive divergent currents in the upper atmosphere that close in and perturb the magnetosphere. We estimate the conductivities and wind speeds required for these perturbations to be significant, and argue that they are most likely to be important at auroral latitudes where the conductivity may be enhanced by particle precipitation.

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Section: Conductivities and Wind Speedsmentioning

confidence: 84%

Periodic modulation of gas giant magnetospheres by the neutral upper atmosphere

Smith

2006

Ann. Geophys.

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“…Thus for the remainculated using the simple analytic expression given in Smith et al (1983) and the constants are given in Table I. As noted above, there does appear to be some difference between the Voyager results and the more recent ground based stellar occultation results (Hubbard et al, 1997). However, this should not affect our results since it is more of a case of an absolute height scale.…”

mentioning

confidence: 83%

“…densities, temperatures, and CH 4 densities, notwithstanding the difference in inferred K h . After we had done our Model Atmosphere calculations, we discovered that Hubbard et al (1997) have presented atmospheric structure information obtained Most of our calculations are based on an atmosphere from the analysis of an extensive data set of immersion derived from the occultation data which we adopt as our and emersion light curves of the occultation of the star 28 reference. There is clearly some uncertainty, not well quanSgr by Saturn's mesosphere.…”

mentioning

confidence: 99%

He 584 Å Dayglow at Saturn: A Reassessment

Parkinson

Griffioen

McConnell

et al. 1998

Icarus

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“…The wave signature is not observed at lower altitudes because the wave amplitude usually decreases with increasing pressure. Atmospheric waves have been observed by stellar occultation in Saturn's upper atmosphere (Hubbard et al, 1997;Cooray et al, 1998), but 35 their parameters (angular frequency, wave-vector) remain unconstrained. It is therefore difficult to assess our hypothesis.…”

Section: Temperature Variationsmentioning

confidence: 99%