Convective storms in Jupiter appear in regions of cyclonic shear or in closed cyclones. In May 31, 2020 a short-lived convective storm appeared in one of the small but long-lived cyclones of the South Temperate Belt (STB). This storm, nicknamed “Clyde’s spot” to honor its discoverer, was imaged by JunoCam 2.5 days later, when its activity had already declined. JunoCam showed a two-sided cyclone with high clouds on methane band and small-scale waves surrounding it that could be gravity waves by their morphology. Later observations showed that the original bright cyclone had turned into a dark spot followed by a trail of turbulence with dark and bright patches that mostly followed the zonal winds. The dark spot itself moved slightly faster than zonal winds at its latitude with small and cyclic variations of its drift rate. About 35° westward of the storm, a dark-red cyclone trailed the original storm and stopped much of the westward-moving turbulence produced by the initial storm. The combination of the two cyclones and turbulence formed an elongated structure similar to elongated white cyclones commonly observed in Jupiter’s STB. One of them, the “so-called STB Ghost”, was home to a system of convective storms in 2018 that we recently studied and whose activity we reproduced using numerical simulations with the EPIC model in which we injected an amount of energy only compatible with water moist convection (Iñurrigarro et al., 2020). While the storm in 2020 appearing in “Clyde’s spot” was less energetic, its global activity shows remarkable similarities with the storm in 2018 in the STB Ghost. We present an observational analysis based in amateur, HST and JunoCam observations of the cyclone before (since April 2019), during the perturbed state (early June 2020) and on its aftermath (July-September 2020). Numerical simulations using the EPIC model show that a small cyclone perturbed by a short-lived storm breaks in two segments that closely resemble the JunoCam observation and rotate cyclonically producing westward moving turbulence. We explore the role of the second trailing cyclone in forming the elongated structure observed since June 2020 and we show numerical simulations that match the observed phenomena. We discuss the relevance of this small-scale storm in comparison with previous larger convective events towards a better understanding of the role of moist convection in Jovian atmospheric dynamics.
Iñurrigarro et al., 2020. Observations and numerical modelling of a convective disturbance in a large-scale cyclone in Jupiter’s South Temperate Belt, Icarus, 336, 113475.