Open AccessZ mode waves as the source of Saturn narrowband radio emissions
Author(s) -
Ye ShengYi,
Menietti J. D.,
Fischer G.,
Wang Z.,
Cecconi B.,
Gurnett D. A.,
Kurth W. S.
Publication year - 2010
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009ja015167
Subject(s) - narrowband , physics , cyclotron , polarization (electrochemistry) , magnetic field , computational physics , plasma , atomic physics , optics , chemistry , nuclear physics , quantum mechanics
We report 5 kHz narrowband Z mode emissions observed by the Cassini Radio and Plasma Waves Science (RPWS) instrument during high latitude perikrone passes. The narrowband emissions observed below the local electron cyclotron frequency ( f ce ) are >20 dB more intense than the usual L‐O mode narrowband emissions observed above local f ce . Polarization measurements show that the narrowband emissions observed below f ce are oppositely polarized to those above f ce , which identifies the emissions below f ce with Z mode. We propose that the L‐O mode narrowband emissions observed at 5 kHz are mode converted from the Z mode waves at a density gradient or density irregularity. The Z mode to L‐O mode conversion via scattering off of density irregularities can also account for the direction finding results of 5 kHz narrowband emissions which point to a source in the auroral zone. We also present the first magnetic field measurements of Saturn narrowband emissions validating their electromagnetic nature.