Contribution of JRM33 model to the study of emission cone of Jovian decameter radiation

The study presented here is a continuation of a series of works where the angular distribution of the Jovian decameter radiation occurrence probability, relatively to the local magnetic field B and its gradient ∇B in the source region is investigated, using the recent magnetic field model for Jupiter, based on Juno’s first 33 polar orbits observations, Jupiter Refence Model JRM33, proposed by Connerney et al. [Journal of Geophysical Research: Planets, 127, 1-15, 2022]. Our results are compared to those obtained earlier using the JRM09 model derived from the first nine orbits of the Juno spacecraft by Connerney et al. [Geophysical Research Letters, 45, 2590-2596, 2018]. The JRM33 model confirms the former findings where the radio emission is beamed in a hollow cone exhibiting a flattening in a specific direction. The Jovian decameter radiation is supposed to be produced by the cyclotron maser instability (CMI). We interpret this flattening by the fact that the magnetic field in the radio source does not have any axial symmetry because B and ∇B are not parallel. This assumption is confirmed by the amplitude of the flattening of the cone which appears to be more important for the northern emission (31.8%) than for the southern one (11.4%) probably due to the fact that the angle between the directions of B and ∇B is greater in the North (~10°) than in the South (~5°). We propose a theoretical study of the propagation and amplification of the waves by the CMI in the radio source in the plane (B, ∇B) as well as in the perpendicular plane aiming to evaluate the emergence angle of the radiation.