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Saturn chorus latitudinal variations
Journal article   Open access   Peer reviewed

Saturn chorus latitudinal variations

J. D. Menietti, G. B. Hospodarsky, Y. Y. Shprits and D. A. Gurnett
Journal of geophysical research. Space physics, Vol.119(6), pp.4656-4667
06/2014
DOI: 10.1002/2014JA019914
url
https://doi.org/10.1002/2014JA019914View
Published (Version of record) Open Access

Abstract

The variation of propagation properties of whistler mode chorus as a function of latitude is not well known at Saturn but is important for the calculation of pitch angle diffusion and nonlinear growth of chorus. The Cassini spacecraft has spent a portion of its orbital time in high-inclination orbits, allowing traversal of the magnetic equator at nearly constant L shell for several passes. This is important since chorus is believed to propagate dominantly close to the magnetic field direction. We have investigated the change of wave normal angle, whistler mode magnetic intensity, and ambient magnetic field inhomogeneity as a function of latitude observed by the Radio and Plasma Wave investigation onboard the Cassini instrument. We find that wave normal angles along a nearly constant L shell remain close to field-aligned, except nearest the equator, and whistler mode wave intensity increases from the magnetic equator, according to a power law. The ambient magnetic field shows an inhomogeneity that is lower than Earth's, but there is a lack of drifting-frequency signatures nearest the equator. The bandwidth of the chorus emission can be described by a simple exponential. The bandwidth increases from the equator, peaking a few degrees away in a region of strong nonlinear growth and then decreases at higher latitudes.
 Astronomy & Astrophysics Physical Sciences Science & Technology

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