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Jupiter’s auroral radio emissions observed by Cassini: rotational versus solar wind control, and components identification
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  • Philippe Zarka,
  • Fabiola P. Magalhaes,
  • M. S Marques,
  • Corentin Kenelm Louis,
  • Ezequiel Echer,
  • Laurent Lamy,
  • Baptiste Cecconi,
  • Renée Prangé
Philippe Zarka
Observatoire de Paris

Corresponding Author:[email protected]

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Fabiola P. Magalhaes
Observatoire de Paris
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M. S Marques
Departamento de Geofísica, Universidade Federal do Rio Grande do Norte
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Corentin Kenelm Louis
Dublin Institute for Advanced Studies (DIAS)
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Ezequiel Echer
National Institute for Space Research (INPE)
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Laurent Lamy
LESIA, Observatoire de Paris, CNRS, PSL
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Baptiste Cecconi
Observatoire de Paris
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Renée Prangé
Observatoire de Paris
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Abstract

Reanalyzing Cassini radio observations performed during Jupiter’s flyby of 2000-2001, we study the internal (rotational) versus external (solar wind) control of Jupiter’s radio emissions, from kilometer to decameter wavelengths, and the relations between the different auroral radio components. For that purpose, we build a database of the occurrence of Jovian auroral radio components bKOM, HOM and DAM observed by Cassini, and then frequency-longitude stacked plots of the polarized intensity of these radio components. Comparing the results obtained inbound and outbound, as a function of the Observer’s or Sun’s longitude, we find that HOM & DAM are dominantly rotation-modulated (i.e. emitted from searchlight-like sources fixed in Jovian longitude), whereas bKOM is modulated more strongly by the solar wind than by the rotation (i.e. emitted from sources more active within a given Local Time sector). We propose a simple analytical description of these internal and external modulations and evaluate its main parameters (the amplitude of each control) for HOM+DAM and bKOM. Comparing Cassini and Nançay Decameter Array data, we find that HOM is primarily connected to the decameter emissions originating from the dusk sector of the Jovian magnetosphere. HOM and DAM components form a complex but stable pattern in the frequency-longitude plane, that remains to be modelled. HOM also seems to be related to the so-called ‘lesser arcs’ identified by Voyager. bKOM consists of a main part above ∼40 kHz in antiphase with HOM occurrence, and detached patches below ∼80 kHz in phase with HOM occurrence.
Oct 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 10. 10.1029/2021JA029780