Jupiter’s Great Red Spot: Strong interactions with incoming anticyclones in 2019

Jupiter’s Great Red Spot (GRS), a giant anticyclone, is the largest and longest-lived of all the vortices observed in planetary atmospheres. During its history, the GRS has shrunk to half its size since 1879, and encountered many smaller anticyclones and other dynamical features that interacted in a complex way. In 2018-2020, while having a historically small size, its structure and even its survival appeared to be threatened when a series of anticyclones moving in from the east tore off large fragments of the red area and distorted its shape. In this work we report observations of the dynamics of these interactions and show that as a result the GRS increased its internal rotation velocity, maintaining its vorticity but decreasing its visible area, and suffering a transient change in its otherwise steady 90-day oscillation in longitude. From a radiative transfer analysis and numerical simulations of the dynamics we show that the interactions affected the upper cloud tops of the GRS. We argue that the intense vorticity of the GRS, together with its larger size and depth compared to the interacting vortices, guarantees its long lifetime.