Speaker
Description
The Waves instrument onboard the Juno spacecraft recorded numerous cases of dispersed
electromagnetic waves generated by Jovian lightning. These waves, also known as whistlers,
propagated through ionospheric and magnetospheric plasmas before their detection by Juno
during its close approaches to Jupiter. We present observations of nearly five thousand low-
dispersion lightning whistlers detected below radial distances of 5 Jovian radii during the first
half of the Juno mission. We have found that Jovian lightning discharges occur predominantly
at mid-latitudes. We have found an asymmetry in the whistler occurrence in both
hemispheres: the average lightning stroke rate in the northern hemisphere was approximately
twice higher than in the southern hemisphere in the first quarter of the mission, but the
mysterious asymmetry surprisingly disappeared in its second quarter. This effect might be
explained by a random distribution of thunderstorms. A lack of whistlers in the tropics might
be a consequence of their propagation in field-aligned ducts which would not allow them to
reach the altitude of Juno. Generation of lightning at Jupiter’s equatorial regions might be also
suppressed due to the solar radiation received at Jupiter’s equator, which actually inhibits the
rise of warm air from within the planet into the upper atmosphere.
