Moist convection drives an upscale energy transfer at Jovian high latitudes

Abstract

Jupiter’s atmosphere is one of the most turbulent places in the solar system. Whereas observations of lightning and thunderstorms point to moist convection as a small-scale energy source for Jupiter’s large-scale vortices and zonal jets, this has never been demonstrated due to the coarse resolution of pre-Juno measurements. The Juno spacecraft discovered that Jovian high latitudes host a cluster of large cyclones with diameter of around 5,000 km, each associated with intermediate- (roughly between 500 and 1,600 km) and smaller-scale vortices and filaments of around 100 km. Here, we analyse infrared images from Juno with a high resolution of 10 km. We unveil a dynamical regime associated with a significant energy source of convective origin that peaks at 100 km scales and in which energy gets subsequently transferred upscale to the large circumpolar and polar cyclones. Although this energy route has never been observed on another planet, it is surprisingly consistent with idealized studies of rapidly rotating Rayleigh–Bénard convection, lending theoretical support to our analyses. This energy route is expected to enhance the heat transfer from Jupiter’s hot interior to its troposphere and may also be relevant to the Earth’s atmosphere, helping us better understand the dynamics of our own planet.

Direct driving of simulated planetary jets by upscale energy transfer

“…These authors, however, employ a slightly less strict definition of a cascade by not including the necessity of local interactions. In agreement with these simulations, Siegelman et al (2022) find an upscale transfer to large scales in the Juno data of Jupiter's polar vortices. The locality of the transfer has, however, not been constrained, and it is an open question as to whether Jupiter's polar vortices are driven by an inverse cascade.…”

“…Finally, an analysis of observational data would be very interesting, such as from the Cassini or Juno missions (e.g., Galperin et al 2014;Young & Read 2017;Siegelman et al 2022). A comparison between observations, deep spherical shell simulations, and shallow general circulation models (e.g., Schneider & Liu 2009;Cabanes et al 2020) may help resolve the question of whether the jet driving is deep or shallow.…”

Zonal jets experiments in the gas giants’ zonostrophic regime

“…1). Because rotation is dominant, the turbulent motions are quasi two-dimensional (2D) and may bear an inverse cascade of kinetic energy (Young and Read, 2017;Siegelman et al, 2022) feeding largescale features (vortices and jets). We denote 𝜖 the corresponding rate of energy transfer.…”

Five Years of Observations of the Circumpolar Cyclones of Jupiter

“…Among convective models, we just note that a recent model by Siegelman et al (2022), not discussed in our previous work, showed that at scales of the order of 100 km or less, turbulence at the Jupiter poles is dominated by shallow convective instabilities that can feed energy to the much larger cyclones.…”