The Robustness of Self-organized Zonal Jets in Unforced, Turbulent Vorticity Fields

A wide parameter space is spanned to check the innuence of numerical parameters on self-organized jets in rotating, turbulent shallow-water ows. It is found that, even in harsh physical (strongly ageostrophic) and numerical ((ltered, hyperviscous, high-resolution) environments, the basic morphogenesis of steady jets, qualitatively reeecting the Rhines scale, is robust. However, detailed features of the jet pattern, such as the amplitude, the width, and the location can be substantially aaected by numerical parameters for a xed set of physical parameters. In general, while the amount of energy lost seems to be a good predictor of maximum jet amplitude and width, a nonmonotonic dependence of these features on the numerical parameters is observed. The most acute sensitivity is associated with the use of a r 16 hyperdissipation operator in conjunction with a Robert-Asselin lter, which leads to substantial meridional shifts of the entire jet pattern as the viscosity coeecient is varied.