Journal article
Cassini observations of narrowband radio emissions in Saturn's magnetosphere
Journal of geophysical research. Space physics, Vol.115(A6), A06213
06/2010
DOI: 10.1029/2009JA014847
Abstract
The Radio and Plasma Wave Science instrument (RPWS) on board the Cassini spacecraft has detected numerous narrowband radio emissions in Saturn's magnetosphere from September 2005 to May 2007. Typically, the narrowband radio emissions occur after an intensification of Saturn kilometric radiation (SKR) and last for several days. These emissions often occur near 5 kHz, with a modulation period of about 10.8 h, similar to the planet's rotation period. Other apparently associated bands also occur at higher frequencies, typically from 20 to 30 kHz. Both 5 kHz and 20 to 30 kHz emissions tend to decrease in intensity with increasing time and slowly drift upward in frequency after the onset. Our study shows that the narrowband radio emissions tend to be observed on the nightside at a radial distance range from 5 to 50 Saturn radii and tend to be observed more frequently at higher latitudes. The rotational modulation of narrowband radio emissions in Saturn's magnetosphere acts like a flashing light rather than a rotating beacon, similar to the source of SKR. These emissions are believed to be generated by mode conversion from anisotropy-driven electrostatic instabilities near the upper hybrid frequency. Comparisons with Cassini neutral particle imaging data show that transient hot plasma clouds, corotating with the planet inside the orbit of Titan, might be the source for narrowband radio emissions. Comparisons with Cassini Magnetometer data reveal that the narrowband radio emissions tend to occur 1 or 2 days after the compression of the magnetotail.
Details
- Title: Subtitle
- Cassini observations of narrowband radio emissions in Saturn's magnetosphere
- Creators
- Z. Wang - University of IowaD. A. Gurnett - University of IowaG. Fischer - Space Research InstituteS. -Y. Ye - University of IowaW. S. Kurth - University of IowaD. G. Mitchell - Johns Hopkins University Applied Physics LaboratoryJ. S. Leisner - University of IowaC. T. Russell - University of California, Los Angeles
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.115(A6), A06213
- DOI
- 10.1029/2009JA014847
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Publisher
- Amer Geophysical Union
- Number of pages
- 12
- Grant note
- 1279973 / Jet Propulsion Laboratory with the University of Iowa
- Language
- English
- Date published
- 06/2010
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455262002771
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