Abstract

This talk examines the emergence of jets and their long-time dynamics in global spherical rotating shallow-water flows.  Departing from many past studies, we apply space and time-varying (time-correlated) topographic-like forcing exclusively, and weakly damp thermally.  Results are presented using Contour Advection, a numerical approach designed to have extremely weak numerical damping, and thus suitable for investigating long-time dynamics.  The response to topographic forcing differs significantly from previously-considered vorticity forcing, with a much larger role played by divergent motions (imbalance).  Like in previous studies, well-defined quasi-zonal jets emerge, but these jets can drift meridionally, which appears to be an effect induced by the divergent motions. Authors: David Dritschel, Richard Scott & Mahdi Jalali