Linear Penetrative Spherical Rotating Convection

Abstract

The onset of penetrative convection in a rotating, gravitationally unstable spherical fluid layer bounded above or below by a stable spherical corotating layer is investigated. Rapid rotation and spherical geometry produce new phenomena in the context of penetrative convection that are fundamentally different from what has been observed in the well-studied plane-layer model. In a slowly rotating or nonrotating spherical system, the character of penetration is qualitatively similar to that in plane fluid layers. In a rapidly rotating spherical system with a spherical layer of stable fluid bounded above by an unstable spherical layer, the stable fluid prevents penetration of convection across the interface between the stable and unstable spherical layers. In the reciprocal situation, however, when a spherical layer of stable fluid is bounded below by an unstable spherical layer, convective motions penetrate from the unstable layer all the way through the outermost stable layer with nearly the same amplitude as in the underlying unstable layer. The phenomena can be explained as a direct consequence of the combined effects of rapid rotation and spherical layer geometry.