Open AccessOn estimating the amplitude of Jovian whistlers observed by Voyager 1 and implications concerning lightning
Author(s) -
Hobara Y.,
Kanemaru S.,
Hayakawa M.,
Gurnett D. A.
Publication year - 1997
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 - 10.1029/96ja03996
Subject(s) - jovian , whistler , physics , ionosphere , van allen radiation belt , amplitude , lightning (connector) , jupiter (rocket family) , geophysics , plasmasphere , atmosphere of jupiter , magnetosphere , range (aeronautics) , computational physics , astrophysics , spacecraft , astronomy , plasma , planet , power (physics) , optics , saturn , quantum mechanics , materials science , composite material
In this paper we extensively reexamine the amplitude of many whistlers detected by the Voyager 1 and try to deduce information about the causative lightning discharges with the use of our ray‐tracing computations taking into account the amplitude. As a result, we have derived the frequency spectra and mean radiation power of the causative lightning discharges and have also applied statistical method to the analysis. We can summarize our findings in the following. The average power flux spectral density of the whistlers falls in a range from 10 −12.7 V 2 m −2 Hz −1 to 10 −11.0 V 2 m −2 Hz −1 . We calculated the total decrease of the whistler amplitude from the bottom of the ionosphere toward the spacecraft, as a range from about 30 to 40 dB. One of the strongest estimated lightning events exhibits a frequency dependence comparable to the terrestrial one, but its peak frequency seems to be similar to the upward current strokes on the Earth. Moreover, the rather smooth profile obtained implies a small possibility of the presence of stratified layers in the Jovian ionosphere. Other events possibly have features similar to those of the terrestrial return strokes. We calculated the mean radiation power per flash of the lightning in the Jovian atmosphere for a 1‐kHz bandwidth over 60 ms, as a range from the order of 10 2 to 10 5 W. The probability distribution of the radiation power in Jupiter is found to follow a lognormal distribution, just as in the terrestrial case.