On the interaction of Jupiter's Great Red Spot and zonal jet streams

TL;DR

This study uses Jupiter's Great Red Spot to infer atmospheric properties like potential vorticity, shear, and entropy gradient, revealing how jet streams influence the GRS's structure and stability.

Contribution

It provides new insights into the interaction between the GRS and jet streams, especially regarding potential vorticity distribution and shear effects, which were previously not well understood.

Findings

Potential vorticity jumps at jet streams influence GRS shear.

Aspect ratio of GRS's vorticity anomaly is about 2:1 due to shear interactions.

Interior potential vorticity is about half of the collar's, indicating unique vortex stability.

Abstract

In this paper, Jupiter's Great Red Spot (GRS) is used to determine properties of the Jovian atmosphere that cannot otherwise be found. These properties include the potential vorticity of the GRS and its neighboring jet streams, the shear imposed on the GRS by the jet streams, and the vertical entropy gradient (i.e., Rossby deformation radius). The cloud cover of the GRS, which is often used to define the GRS's area and aspect ratio, is found to differ significantly from the region of the GRS's potential vorticity anomaly. The westward-going jet stream to the north of the GRS and the eastward-going jet stream to its south are each found to have a large potential vorticity ``jump''. The jumps have opposite sign and as a consequence of their interaction with the GRS, the shear imposed on the GRS is reduced. The east-west to north-south aspect ratio of the GRS's potential vorticity anomaly depends on the ratio of the imposed shear to the strength of the anomaly. The aspect ratio is found to be $\approx$2:1, but without the opposing jumps it would be much greater. The GRS's high-speed collar and quiescent interior require that the potential vorticity in the interior be approximately half that in the collar. No other persistent geophysical vortex has a significant minimum of potential vorticity in its interior and laboratory vortices with such a minimum are unstable.