Many thanks to: STEREO and WIND
Teams, Taxpayers of France, French Air Force, Nancay Decametric Array
Team at the Nancay Radio Astronomy Station of Paris Observatory, Prof.
Dr. Kazumasa Imai Kochi National College of Technology Kochi Japan,
Trinity College Dublin Ireland Astrophysics Group, United States NOAA
SWPC, NASA Solar Dynamics Observatory Teams, Lockheed Martin Solar Laboratory, SOTERIA Project
"The
Jupiter encounter by the Cassini spacecraft in late 2000 and early 2001
unveiled persistent properties of Jupiter's hectometric (HOM) radiation
originating along auroral magnetic field lines in the polar regions.
One of the unique properties of the HOM dynamic spectrum, known as
attenuation lanes, appears as rotationally modulated, well-defined
regions of lowered intensity, flanked by regions of enhancement. These
lanes seem to be the result of refraction of radio waves in a
high-density medium–either caused by Case (i) enhanced density in the
magnetic L-shell connected to Io's orbit or Case (ii) in the Io plasma
torus itself or both. In this paper, we investigate the HOM ray paths of
0.5–3.0 MHz emissions with various cone half-angles in the continuous
radio longitudes generating at the magnetic L-value equal to 30. We use
bi-kappa particle distributions to derive diffusive equilibrium
distributions of density in the Io plasma torus. The enhanced density
irregularities along the Io flux shell “ribbon” region can be described
with a Gaussian density distribution of a maximum density n0 and breadth
(half-width of the distribution across the flux shell) sigma. As a
result, we found that the interpretation of Case (i) can be accounted
for by the attenuation lanes which appear for all cone half-angles, and
the reasonable flux shell density n0 is, on top of specific
latitude-dependent density from the diffusive equilibrium model,
estimated as 100 per cubic cm with the half-width sigma = 5.0 Io radii."