Effect of transient vortex interactions on the size and strength of Jupiter’s Great Red Spot

Abstract

Jupiter’s Great Red Spot (GRS) is among the largest discrete weather features in the Solar System. Although observed for at least 200 years, the GRS is shrinking, particularly in the past 50 years. Studies of long-lived terrestrial anticyclonic features, known as blocks, demonstrate that they can be sustained, in part, by interactions with transient vortices. Motivated by these results and observations of the GRS absorbing smaller vortices, we conduct three-dimensional simulations of a GRS-like vortex. Control simulations omit forced vortex interactions, while a set of experimental simulations include GRS interactions with transient anticyclones of varying frequency and intensity. Comparison of these simulations allows isolation of the role of such mergers in the GRS evolution. We find that the GRS is larger following periodic vortex interactions relative to control simulations without mergers. Similarly, analysis of upper troposphere eddy potential vorticity and dynamic tropopause potential temperature anomalies suggests the GRS is strengthened by vortex interactions. The degree to which the GRS is sustained increases with interaction frequency and transient anticyclone intensity. These results are consistent with terrestrial blocking dynamics and support the theory that the GRS is modulated by persistent interactions with smaller vortices.