A planetary‐scale disturbance in the most intense Jovian atmospheric jet from JunoCam and ground‐based observations

Abstract

We describe a huge planetary‐scale disturbance in the highest‐speed Jovian jet at latitude 23.5°N that was first observed in October 2016 during the Juno perijove‐2 approach. An extraordinary outburst of four plumes was involved in the disturbance development. They were located in the range of planetographic latitudes from 22.2° to 23.0°N and moved faster than the jet peak with eastward velocities in the range 155 to 175 m s−1. In the wake of the plumes, a turbulent pattern of bright and dark spots (wave number 20–25) formed and progressed during October and November on both sides of the jet, moving with speeds in the range 100–125 m s−1 and leading to a new reddish and homogeneous belt when activity ceased in late November. Nonlinear numerical models reproduce the disturbance cloud patterns as a result of the interaction between local sources (the plumes) and the zonal eastward jet.

Temporal and spatial variations of the absolute reflectivity of Jupiter and Saturn from 0.38 to 1.7μm with PlanetCam-UPV/EHU

“…This corresponds to the evolution of an eruption in the NTB in 2012 close to solar conjunction that could not be observed properly. A similar phenomena was observed in 2007 (Sánchez-Lavega et al 2008) and 2017 (Sánchez-Lavega et al 2017).…”

“…First channel (visible; VIS) covers wavelengths below 1 µm and the second channel (short-wave infrared; SWIR) works above this value and up to 1.7 µm. PlanetCam images have been used so far for several works on Jupiter (Hueso et al 2017b;Sánchez-Lavega et al 2017), Saturn (Sánchez-Lavega et al 2014, 2016a, Venus (Sánchez-Lavega et al 2016b), and Neptune (Hueso et al 2017a). …”

Jupiter cloud morphology and zonal winds from ground‐based observations before and during Juno's first perijove

“…Differences between the 2016 zonal winds and Cassini winds concentrate in (i) the North Temperate Belt (NTB) with intense zonal winds in 2015 [ Simon et al ., ] and 2016 possibly required for the development of large‐scale disturbances [ Sánchez‐Lavega et al , , ], (ii) the NEB where the presence of large dark projections moving more slowly than the winds makes zonal winds apparently less intense [ Asay‐Davis et al , ; Barrado‐Izagirre et al , ; Choi et al , ], and (iii) the peak of the SEB jet where a wave system partially observed over 2015 may also affect the zonal winds resulting in less intense motions [ Rogers et al , ].…”

“…Zonal winds could be measured over different temporal periods without noticeable changes except for a high value of the NTB jet which peaked at 157 ± 3 m s −1 . These high speeds of the NTB jet seem to occur previous to the development of large‐scale convective outbreaks [ Sánchez‐Lavega et al , ] as the one developed in October 2016 [ Sánchez‐Lavega et al , ]. PlanetCam observations of the polar regions at filters not sensitive to methane absorption provide dynamical context to the high‐resolution polar observations of JunoCam [ Orton et al , ].…”

Cycles of activity in the Jovian atmosphere

“…What came next was even more spectacular— Sánchez‐Lavega et al . [] report the eruption of four extraordinary plumes near Jupiter's fastest eastward jet at 23.9°N, characteristic of another cycle of atmospheric variability in the North Temperate Belt (NTB) [ Sánchez‐Lavega et al , , ]. The October 2016 NTB eruption was remarkable for several reasons: (i) Juno had just arrived in the Jovian system to observe the phenomenon; (ii) four plumes at widely separated longitudes were identified; and (iii) the Earth‐based support campaign was able to provide remarkable temporal coverage even though Jupiter was still relatively close to solar conjunction.…”