Advanced Ocean Modelling: Using Open-Source Software

3.14 Oceanic Convection 59Considerations of Rayleigh numbers are useful for studies of the onset of convectionin laboratory settings and computer-based simulations. Values of criticalflux-Rayleigh numbers in the real situation, however, are not known with any certainty.3.14.4 Aspect Ratio of Convection CellsThe distance of adjacent convective plumes is typically twice their penetration depth(Turner, 1973), which can be expressed in terms of a geometric ratio called aspectratio of convection cells (Fig. 3.30). This knowledge is useful for adequate choicesof grid spacings and model-domain size. Recall that the length scale of a processshould be spatially resolved by at least 10 grid points and that the size of the modeldomain should exceed this length scale several times. A penetration depth of 100 m,for instance, suggests the use of horizontal and vertical grid spacings of