The Convection and Corotation Electric Field in the Jovian Magnetosphere

Jovian magnetospheric dynamics are governed by two distinct mass-energy circulation mechanisms: the solar-wind-driven Dungey cycle and the Vasyliūnas cycle governed by planetary rapid rotation and internal plasma sources. Jovian electric field spatial distribution can provide key insights into quantifying the contribution from the Dungey cycle and the Vasyliūnas cycle. In this study, we establish a nightside equatorial electric field model (10–30 Jupiter radii) through inference calculations utilizing Juno spacecraft observations. We find that the total electric field is primarily directed radially outward, indicating the dominance of the Vasyliūnas cycle in this region. The field also exhibits a local time asymmetry, with weaker intensity in the dusk sector. After decomposing the total electric field into corotation and convection components, we find the corotation electric field shows a power-law exponent of −2.69. Moreover, the convection component displays a clear azimuthal difference: it is inward-oriented at 16–22 MLT, suggesting sunward plasma flow, while exhibiting a westward orientation at 22–05 MLT, indicative of radially outward transport. These findings elucidate the interplay between rotational and solar-wind-driven circulation, advancing our understanding of magnetospheric dynamics from the electric field viewpoint.