A model to determine open or closed cellular convection

A simple mechanism is proposed to explain the observed presence in the atmosphere of open or closed cellular convection. If convection is produced by cooling concentrated near the top of the cloud layer, as in radiative cooling of stratus clouds, it develops strong descending currents which are compensated by weak ascent over most of the horizontal area, and closed cells result. Conversely, heating concentrated near the bottom of a layer, as when an air mass is heated by warm water, results in strong ascending currents compensated by weak descent over most of the area, or open cells. This mechanism is similar to the one suggested by Stommel (1962) to explain the smallness of the oceans' sinking regions. The mechanism is studied numerically by means of a two-dimensional, nonlinear Boussinesq model.