An Analysis of Stochastic Jovian Oscillation Excitation by Moist Convection

TL;DR

This study investigates whether moist convection in Jupiter's atmosphere can excite observed global oscillations, finding that thermal energy, rather than kinetic energy, may be sufficient to drive these modes if adequately available.

Contribution

The paper introduces a stochastic excitation model showing moist convection's potential to drive Jovian oscillations through thermal energy, despite kinetic energy limitations.

Findings

Kinetic energy from storms is insufficient to excite oscillations.

Thermal energy associated with moist convection can potentially drive the modes.

Storm energy requirements for excitation are 5×10^{27} to 10^{28} erg per day.

Abstract

Recent observations of Jupiter have suggested the existence of global oscillatory modes at millihertz frequencies, yet the source mechanism responsible for driving these modes is still unknown. However, the energies necessary to produce observable surface oscillations have been predicted. Here we investigate if moist convection in Jupiter's upper atmosphere can be responsible for driving the global oscillations and what moist convective energy requirements are necessary to achieve these theoretical mode energies and surface amplitudes. We begin by creating a one-dimensional moist convective cloud model and find that the available kinetic energy of the rising cloud column falls below theoretical estimates of oscillations energies. That is, mode excitation cannot occur with a single storm eruption. We then explore stochastic excitation scenarios of the oscillations by moist convective storms. We find that mode energies and amplitudes can reach theoretical estimates if the storm energy available to the modes is more than just kinetic. In order for the modes to be excited, we find that they require $5 \times 10^{27}$ to 10$^{28}$ erg per day. However, even for a large storm eruption each day, the available kinetic energy from the storms falls two orders of magnitude short of the required driving energy. Although our models may oversimplify the true complexity of the coupling between Jovian storms and global oscillations, our findings reveal that enough thermal energy is associated with moist convection to drive the modes, should it be available to them.