beta plane corrections to nonlinear atmospheric flow patterns application to jupiters great red spot (GRS) drift dynamics
Oladiran Johnson Abimbola
TL;DR
The paper extends the f-plane description of Jupiter’s Great Red Spot to a β-plane framework by incorporating the meridional gradient of planetary vorticity, characterized through the Rossby parameter $\beta$ and the deformation parameter $\gamma$. Using a thin-shell, far-from-equilibrium perturbation approach with a Lagrangian formulation, it derives an analytic westward drift velocity $c_R\approx-3.7$ to $-3.9\mathrm{m\,s^{-1}}$ in close agreement with observations, and explains a 90-day oscillation as a beat between vortex rotation and Rossby waves. The β-plane model also reveals meridional asymmetry in winds, a quadratic pressure correction, and a latitudinally varying PV field, while demonstrating broad universality across Saturn, Neptune, and Earth without free parameters. The study discusses the regime of validity ($\gamma\lesssim0.5$), potential time-dependent extensions, and applications to exoplanets and other planetary vortices, highlighting the critical role of planetary vorticity gradients in long-lived atmospheric vortex dynamics.
Abstract
The Great Red Spot (GRS) of Jupiter has been observed for over a century, with researchers studying its characteristics and dynamics, including its size, depth, movement, and interactions with its environment. Recently, the f-plane thin-shell asymptotic analysis was used to explain some of the GRS features, but the method failed to capture the observed westward drift of the GRS. In this study, the f-plane theory was extended by including the Rossby parameter in the β-plane approximation and using the dimensionless Rossby deformation parameter γ, to systematically apply perturbation theory. The westward drift velocity of 3.7 m/s was analytically predicted, which is 95% in agreement with the observed 3.9 m/s. The observed 90-day oscillation in drift rate was explained. Also explained is the north-south asymmetry in circulation patterns. The universality of the \b{eta}-plane theory was demonstrated by its application to the vortices on Saturn, Neptune and Earth, without free parameters. It was demonstrated in this study that for the understanding of long-lived atmospheric vortex dynamics, the planetary vorticity gradient is very critical.
