Classification of spectral fine structures of Saturn kilometric radiation

Abstract. The spectral fine structures of Saturn kilometric radiation (SKR) are best investigated with the wideband receiver (WBR) Cassini's Radio and Plasma Wave Science (RPWS) instrument, which measured radio fluxes can be displayed in time–frequency spectra resolutions 125 ms ∼0.1 kHz. We introduce seven different classes SKR ranging from dots (one class for 0-dimensional objects) over lines (four 1-dimensional objects being horizontal, vertical, or negative positive slope) to areal features 2-dimensional objects). Additionally, we define a seventh containing special named according their appearance spectra. These rain, striations, worms, caterpillar latter two have never been described literature so far. Using this newly defined classification scheme, classify at low frequencies baseband 80 kHz WBR medium around 325 A statistic occurrence various sub-classes shows some notable characteristics: slope much more common than vertical almost absent frequencies. particular structure striations (group narrowbanded predominantly slopes) is quite below but less near At these frequencies, rather look like interrupted term name “rain”. also find rare instances absorption signatures within features. introduced worms (lines oscillating frequency) caterpillars occur exclusively Caterpillars typical bandwidth ∼10 kHz, constant frequency ∼40 several hours they mostly observed beyond distances 10 radii. discuss implications our findings view many theories about auroral emissions.