Prospects for observing atmospheric gravity waves in Jupiter’s thermosphere using H3+ emission

We propose the use of H3+ thermal emission as a tracer for wave activity present in Jupiter’s ionosphere. We model the effect of atmospheric gravity waves on the ion distribution and the H3+ thermal emission using a two-dimensional time-dependent model of the wave–ion interaction including ion dynamics, diffusion and chemistry. The model is applied to a broad range of wave parameters to investigate the sensitivity of the observations to the wave amplitude, wavelength, period, and direction of propagation for different latitudes and magnetic field orientations. We find that the impact on the H3+ emission is optimized for waves with large vertical and horizontal wavelengths that achieve maximum amplitude at or near the hight of maximum H3+ density (roughly 550 km above the 1 bar pressure level). Larger effect is expected from waves with larger amplitudes. Waves that travel in north/south direction are easier to detect than waves propagating zonally. The model also predicts that the largest signal is to come from waves present at middle latitudes.Our analysis shows that atmospheric gravity waves with parameters consistent with the Galileo Probe observations can leave observable signatures in the H3+ thermal emission at 3.4 μm resulting in 5–23% emission variation along the horizontal path of the wave.

► H3+ IR emission is proposed as a tracer for gravity waves in Jupiter’s thermosphere.
► The signal is largest at midlatitudes for AGWs traveling along the magnetic meridian.
► AGWs that peak at the H3+ density maximum and have large λz have the largest effect.
► AGWs detected by the Galileo Probe can induce observable signal in the H3+ emission.