Jupiter's unearthly jets: a new idealized model

A longstanding mystery about Jupiter has been the straightness of real Jovian jets, quite unlike terrestrial strong jets with their characteristic long-wavelength meandering. The problem is addressed in two steps. The first is to take seriously the classic Ingersoll-Cuong, Dowling-Ingersoll and Stamp-Dowling scenarios, with deep zonal jets in the underlying convection zone, recognizing moreover the relevance of Arnol'd's second shear-stability criterion and hence the possibility of stable upper jets even with reversed upper potential-vorticity gradients. The second step is to improve the realism of the small-scale forcing used to represent the effects of Jupiter's thunderstorms in physical space. The real thunderstorms are likely to generate cyclonic as well as anticyclonic potential-vorticity anomalies, but with unequal strengths, and to occur preferentially where the interface to the deep flow is coldest. The model appears to have promise as a way of explaining the jet straightness and of constraining possible values of Rossby deformation lengths for the real planet, as well as suggesting new guidelines for general circulation model studies.