Radio and Plasma Wave Observations at Saturn from Cassini's Approach and First Orbit

Gurnett, D. A.; Kurth, W. S.; Hospodarsky, G. B.; Persoon, A. M.; Averkamp, T. F.; Cecconi, Baptiste; Lecacheux, A.; Zarka, Philippe; Canu, P.; Cornilleau‐Wehrlin, N.; Galopeau, Patrick H. M.; Roux, A.; Harvey, C. C.; Louarn, P.; Boström, R.; Gustafsson, G.; Wahlund, Jan‐Erik; Desch, M. D.; Farrell, W. M.; Kaiser, M. L.; Goetz, K.; Kellogg, P. J.; Fischer, G.; Ladreiter, H. P.; Rücker, H. O.; Alleyne, H.; Pedersen, Å.

doi:10.1126/science.1105356

Cited by 242 publications

(254 citation statements)

References 23 publications

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“…The periodicity observed in Saturn kilometric radiation (SKR) is a good example of these periods (Gurnett et al, 2005). Periodic variations were also found in the magnetic field (Espinosa and Dougherty, 2000;Andrews et al, 2008Andrews et al, , 2012.…”

Section: Introductionmentioning

confidence: 90%

The latitudinal structure of the nightside outer magnetosphere of Saturn as revealed by velocity moments of thermal ions

et al. 2015

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Abstract. In this study we investigate the latitudinal behavior of the azimuthal plasma velocities in the outer magnetosphere of Saturn using the numerical ion moments derived from the measurements of the Cassini Plasma Spectrometer. One of the new results presented is that although these moments display some scatter, a significant positive correlation is found to exist between the azimuthal velocity and the plasma density, such that on average, the higher the density the higher the rotation speed. We also found that both the azimuthal velocity and the density anticorrelate with the magnitude of the radial component of the magnetic field and drop rapidly with increasing distance from the magnetic equator. The azimuthal velocities show periodic behavior with a period near the planetary rotation period, which can also be explained by the strong dependence on magnetic latitude, taking into account the flapping of the magnetodisk. It is thus found that the dense plasma near the magnetic equator rotates around the planet at high speed, while the dilute plasma at higher latitudes in the northern and southern hemispheres rotates significantly slower. The latitudinal gradient observed in the azimuthal speed is suggested to be a direct consequence of the sub-corotation of the plasma in the outer magnetosphere, with highest speeds occurring on field lines at lowest latitudes mapping to the rapidly rotating inner regions of the plasma sheet, and the speed falling as one approaches the lobe, where the field lines are connected to strongly subcorotating plasma.

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Section: Introductionmentioning

confidence: 90%

The latitudinal structure of the nightside outer magnetosphere of Saturn as revealed by velocity moments of thermal ions

et al. 2015

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“…A similar body of information is currently being gathered at Saturn by the Cassini orbiter (e.g. Bunce et al, 2005;Dougherty et al, 2005;Gurnett et al, 2005;Young et al, 2005), now also including energetic neutral atom imaging of magnetospheric dynamics (e.g. Krimigis et al, 2005;Paranicas et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

2007

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Abstract. We consider the contribution of the solar winddriven Dungey-cycle to flux transport in Jupiter's and Saturn's magnetospheres, the associated voltages being based on estimates of the magnetopause reconnection rates recently derived from observations of the interplanetary medium in the vicinity of the corresponding planetary orbits. At Jupiter, the reconnection voltages are estimated to be ∼150 kV during several-day weak-field rarefaction regions, increasing to ∼1 MV during few-day strong-field compression regions.The corresponding values at Saturn are ∼25 kV for rarefaction regions, increasing to ∼150 kV for compressions. These values are compared with the voltages associated with the flows driven by planetary rotation. Estimates of the rotational flux transport in the "middle" and "outer" magnetosphere regions are shown to yield voltages of several MV and several hundred kV at Jupiter and Saturn respectively, thus being of the same order as the estimated peak Dungeycycle voltages. We conclude that under such circumstances the Dungey-cycle "return" flow will make a significant contribution to the flux transport in the outer magnetospheric regions. The "return" Dungey-cycle flows are then expected to form layers which are a few planetary radii wide inside the dawn and morning magnetopause. In the absence of significant cross-field plasma diffusion, these layers will be characterized by the presence of hot light ions originating from either the planetary ionosphere or the solar wind, while the inner layers associated with the Vasyliunas-cycle and middle magnetosphere transport will be dominated by hot heavy ions originating from internal moon/ring plasma sources. The temperature of these ions is estimated to be of the order of a few keV at Saturn and a few tens of keV at Jupiter, in both layers.

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“…Probably, the same result could be expected on Titan having no constant magnetic field (A. P. Nickolaenko, private communication, 2006). There is little doubt, however, on the basis of the Voyager, Galileo and Cassini missions, that lightning discharges are prevalent on Jupiter [Magalhães and Borucki, 1991] and Saturn [Gurnett et al, 2005], and that lightning is also believed to occur on Uranus [Zarka and Pedersen, 1986] and Neptune [Kaiser et al, 1991]. Titan is also considered as a probable harbor of lightning activity [Tokano et al, 2005], and the dust storms of Mars have been modeled to display electrostatic activity .…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

2006

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[1] The conducting ionosphere and conducting surface of Titan, Venus, and Mars form a concentric resonator, which would support the possibility of the existence of global electromagnetic resonances. On Earth, such resonances are commonly referred to as Schumann resonances and are excited by lightning discharges. The detection of such resonances on other planets would give a support for the existence of the electrical discharges in the lower atmosphere on these planets. In this paper, a three-dimensional finite difference time domain modeling for the extremely low frequency propagation is employed to study the Schumann resonance problems on Titan, Venus, and Mars. The atmospheric conductivity profiles for these studies are derived from the previously reported ionospheric models for these planets. The Schumann resonance frequencies and Q factors on these planets are calculated and are critically compared with those obtained from the previously published models.

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Radio and Plasma Wave Observations at Saturn from Cassini's Approach and First Orbit

Cited by 242 publications

References 23 publications

The latitudinal structure of the nightside outer magnetosphere of Saturn as revealed by velocity moments of thermal ions

The latitudinal structure of the nightside outer magnetosphere of Saturn as revealed by velocity moments of thermal ions

Significance of Dungey-cycle flows in Jupiter's and Saturn's magnetospheres, and their identification on closed equatorial field lines

Three‐dimensional finite difference time domain modeling of the Schumann resonance parameters on Titan, Venus, and Mars

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