A Survey of Small‐Scale Waves and Wave‐Like Phenomena in Jupiter's Atmosphere Detected by JunoCam

Abstract

In the first 20 orbits of the Juno spacecraft around Jupiter, we have identified a variety of wave‐like features in images made by its public‐outreach camera, JunoCam. Because of Juno's unprecedented and repeated proximity to Jupiter's cloud tops during its close approaches, JunoCam has detected more wave structures than any previous surveys. Most of the waves appear in long wave packets, oriented east‐west and populated by narrow wave crests. Spacing between crests were measured as small as ~30 km, shorter than any previously measured. Some waves are associated with atmospheric features, but others are not ostensibly associated with any visible cloud phenomena and thus may be generated by dynamical forcing below the visible cloud tops. Some waves also appear to be converging, and others appear to be overlapping, possibly at different atmospheric levels. Another type of wave has a series of fronts that appear to be radiating outward from the center of a cyclone. Most of these waves appear within 5° of latitude from the equator, but we have detected waves covering planetocentric latitudes between 20°S and 45°N. The great majority of the waves appear in regions associated with prograde motions of the mean zonal flow. Juno was unable to measure the velocity of wave features to diagnose the wave types due to its close and rapid flybys. However, both by our own upper limits on wave motions and by analogy with previous measurements, we expect that the waves JunoCam detected near the equator are inertia‐gravity waves.

Jupiter's Overturning Circulation: Breaking Waves Take the Place of Solid Boundaries

“…Since the EMF eddies are accelerating both the eastward and westward jets, it is natural to assume that the phase speeds c of the waves are similarly bounded by the jet speeds. Most of the mesoscale waves, which have wavelengths around 300 km, are inertia-gravity waves ( Orton et al, 2020 ), and they satisfy this criterion—their phase speeds are <50% and often <10% of the zonal flow speeds, regardless of direction ( Arregi et al, 2009 ; Hunt & Muller, 1979 ; Orton et al, 2020 ; Simon et al, 2015 ). So, we choose a reference frame that has eastward jets on the poleward sides of the zones and westward jets on their equatorward sides, and we assume c = 0 in that frame.…”

Jupiter Science Enabled by ESA’s Jupiter Icy Moons Explorer

“… 2009 ) and Juno imaging (Orton et al. 2020 ), and interpreted to be gravity (i.e., buoyancy waves in a stably-stratified atmosphere) or inertia-gravity waves (i.e., sensing the Coriolis effect). Mesoscale waves modulating cloud opacity and reflectivity, often found in regions of cyclogenesis, have been observed by the Hubble Space Telescope (HST, Fig.…”

Jupiter’s Equatorial Quasi-quadrennial Oscillation Forced by Internal Thermal Forcing

“…Evidence shows vigorous wave activities in Jupiter's atmosphere, especially in the equatorial region (e.g., Rogers & Mettig 2008;Asay-Davis et al 2011;Simon-Miller et al 2012). Most of these wave features appear within ±5°of latitude (Simon-Miller et al 2015;Orton et al 2020), and they exhibit diversity and complexity with various zonal wavenumbers, including waves with wavenumbers between 17 and 70 (Harrington et al 1996;Cosentino et al 2017a). Simon-Miller et al (2012 showed that these waves consist of wavenumbers 75 and and have a phase speed of 101 ± 3 m s −1 , which are likely inertia-gravity waves.…”