Power spectrum of electrical discharges seen on Earth and at Saturn

Journal Article · Sat Jul 01 04:00:00 EDT 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA07p08757· OSTI ID:5833017

Warwick, J W ^[1]

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1. Radiophysics, Inc., Boulder, CO (USA)

The author presents a method for deriving the radio spectrum of electrical discharges from the properties of the time series of charges crossing the discharge gap. This result is applied to the observed spectra of both terrestrial lightning and Saturn electrical discharge(s) (SED). SED occurrence and power density are shown to have subtle, yet important, differences from these observables as they have been described in the last 5 years. It is demonstrated that throughout the episode of Voyager 1's (V1) closest approach to Saturn, SED probably occurred continuously in frequency upward at least from the upper limit of Saturn kilometric radiation at about 800 kHz. This is so despite the fact that in the dynamic spectra a strip in time and frequency in which SED do not occur extends in frequency from 1.3 MHz up to the oft-discussed lower limit of SED in the leading edge of the episode of closest approach. The greater power in SED that occurred after V1 closest approach is emphasized: it is shown to be consistent with the lower frequency of the maximum in their power spectra. The variable gap length factor is also invoked to explain the variable frequency cutoff in the range 5-15 MHz of the episodes before closest approach. The SED source moved along a single arc defining both preencounter and postencounter events. The discharge gap lengths were a continuous function of position along this arc, with the shortest gaps lying about 5{degree} west (as seen from the spacecraft) of the noon meridian of Saturn and the longest gaps lying on the nightside of the planet.

• OSTI ID: 5833017
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A7; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
640200 -- Atmospheric Physics
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ASTRONOMY
ATMOSPHERES
CALCULATION METHODS
EARTH ATMOSPHERE
ELECTRIC DISCHARGES
ELECTROMAGNETIC RADIATION
LIGHTNING
LONG WAVE RADIATION
MATHEMATICS
PLANETARY ATMOSPHERES
PLANETS
RADIATIONS
RADIOASTRONOMY
RADIOWAVE RADIATION
SATURN PLANET
SPACE VEHICLES
TIME-SERIES ANALYSIS
VEHICLES
VOYAGER SPACE PROBES