The Great Red Spot is an enduring large anticyclone in Jupiter's atmosphere, situated in the South Tropical Zone (Figure 1). Anticyclonic flow in this zone is perturbed over the northern edge of the GRS so that it locally protrudes into the typically dark and reddish South Equatorial Belt (SEB) to the north. The SEB features dramatic global-scale changes in coloration, cloud properties, and convective activity (e.g., Fletcher et al., 2011Fletcher et al., , 2017Rogers, 1995;Sánchez-Lavega & Gómez, 1996), but the most notable change in the GRS itself is more monotonic in nature: a continuous decrease in size over more than 100 years of accurate observations (Simon et al., 2018).The size and longevity of the GRS make it unique among outer solar system vortices, yet it also serves as an archetype of a class of "pancake vortices"-anticyclones embedded in stably stratified fluids-also including vortices like the dark spots on Neptune and salt lens eddies in the Earth's oceans (e.g., Dowling, 1995;Hassanzadeh et al., 2012;Yim et al., 2016). Pancake vortices have a thickness much smaller than their horizontal dimensions, like the GRS whose horizontal scale is some 50 times greater than vertical scale, according to theoretical arguments based on laboratory experiments and Jovian vortex velocity fields (Lemasquerier et al., 2020). Terrestrial ocean eddies transport heat meridionally by both stirring (turbulent) and trapping (bulk transport) mechanisms (Sun et al., 2018). Trapping is limited on Jupiter because major vortices are bounded by jets that limit meridional migration, although trapping could be significant on Saturn, where poleward migration of the anticyclone created by the 2010 Great White Storm was observed