L-bursts in Jupiter's decametric radio spectra

Abstract

Dynamic spectra of Jupiter's L-bursts are observed with high-resolution radio spectrographs. The L-bursts are characterized by their emission envelopes. The duration of envelopes varies from one to a few seconds increasing towards the opposition of Jupiter to reach a maximum in the vicinity of 10 to 20 d after opposition. Modulation lanes appear within the emission envelopes. The magnitude of the f-t slopes of lanes is determined by the central meridian longitude (CML) of Jupiter, and partly by the longitude of Io. The sign of the slopes depends on the CML only. The yearly averages for thef-t slopes do not seem to be related to the Jovicentric declination of the Earth. Most lanes are relatively faint. A summary of the properties of modulation lanes is given. A peculiar case of polarization of an L-burst is shown. Certain 'shadow events' are interpreted as occultation effects caused by overdense meteor trails drifting in the upper atmosphere winds.

Fast and slow frequency-drifting millisecond bursts in Jovian decametric radio emissions

“…Figure 2 shows several examples of dynamic spectra of Jovian decametric L emission actually possessing frequency drifting millisecond structures resembling S bursts. This type of spectral structure is different from the phenomenon of modulation lanes reported in earlier papers (Ellis 1975;Riihimaa 1970Riihimaa , 1978Imai et al 1997), since it has a much faster (and typically negative) frequency drift rate in the range of −5 MHz/s to −6 MHz/s, and shorter timescale of amplitude variation at fixed frequency (10−20 ms). These numbers should be compared to ±20 kHz/s to ±300 kHz/s drift rates in Riihimaa (1978) and 2−10 s timescales in .…”

“…This type of spectral structure is different from the phenomenon of modulation lanes reported in earlier papers (Ellis 1975;Riihimaa 1970Riihimaa , 1978Imai et al 1997), since it has a much faster (and typically negative) frequency drift rate in the range of −5 MHz/s to −6 MHz/s, and shorter timescale of amplitude variation at fixed frequency (10−20 ms). These numbers should be compared to ±20 kHz/s to ±300 kHz/s drift rates in Riihimaa (1978) and 2−10 s timescales in . Somewhat similar although slower drifting modulation lanes (−2 MHz/s) were called "fast lane" (FL) bursts in (Ellis 1975).…”

“…The improvement of observational facilities, principally the backend spectrometers, which were upgraded from analog filter banks and videotape recorders (Ellis 1973) to semi-digital acousto-optical spectrum analysers (Riihimaa 1975;Ryabov et al 1997) and digitized videotape (Carr 1999), and then fully digital baseband receivers (Litvinenko et al 2004;Ryabov et al 2007Ryabov et al , 2010Koshida et al 2010), revealed a very complex morphology in the fine structure of Jovian decametric emissions. This led to the introduction of numerous new descriptive types of Jovian decametric radiation, including narrowband (N or NB) emissions (Riihimaa 1985;Boudjada et al 2000;Oya et al 2002), fast L bursts (Ellis 1974), L burst lanes (Ellis 1975;Riihimaa 1970Riihimaa , 1978, tilted-V patterns (Riihimaa 1990), S burst trains, "tulip" . a) Dynamic spectrum containing a sequence of simple quasi linearly drifting S burst (QS).…”

Planetary radio astronomy: Earth, giant planets, and beyond

“…Depending on the time scales, the Jovian DAM exhibits different complex spectral structures. The S-bursts of DAM are detected as very short (milliseconds) impulsive spikes with fast drift in the time-frequency plane (Riihimaa, 1970(Riihimaa, , 1977Leblanc et al, 1980). The occurrence of the S-bursts observation depends on the orbital position of the satellite Io.…”

Modulation structures in the dynamic spectra of Jovian radio emission obtained with high time-frequency resolution

“…Several authors have investigated the modulation events, and some of their results can be found in Gordon & Warwick (1967); Riihimaa (1968Riihimaa ( , 1970Riihimaa ( , 1978Riihimaa ( , 1979Riihimaa ( , 1988Riihimaa ( , 1991; Riihimaa et al (1970); ; Zheleznyakov & Shaposhnikov (1979); Meyer-Vernet et al (1981); Warwick & Dulk (1964); Lecacheux (1976); Ladreiter et al (1995); Imai et al (1997); Arkhypov & Rucker (2007). For instance, Faraday rotation of the polarization plane in the Jupiter decameter signal was Article published by EDP Sciences considered in detail by Warwick & Dulk (1964); Lecacheux (1976); Ladreiter et al (1995); Shaposhnikov et al (1999).…”