Overshooting above a convection zone

As compressible convection has inherent up/down asymmetry, overshooting above and below a convection zone behave differently. In downward overshooting, the narrow downflow columns dynamically play an important role. It is customary, and reasonable, to use the downward flux of kinetic energy as a proxy for overshooting. In the upward situation, the flux of kinetic energy can take on different signs near the upper boundary of the convection zone, and its magnitude is generally small. It cannot make a good proxy for overshooting. This paper discusses the results of a set of numerical experiments that investigate the problem of overshooting above a convection zone. Particle tracing and color advection are used to follow the mixing process. The overshoot region above a convection zone is found to contain multiple counter cell layers.