Comments on ‘‘A Spectral Parameterization of Drag, Eddy Diffusion, and Wave Heating for a Three-Dimensional Flow Induced by Breaking Gravity Waves’’

摘要

In a recent paper Zhu et al. (2010, hereafter Z10) developed a single-column parameterization of the effects of unresolved gravity wave breaking on the grid-resolved flow of a climate model. They discuss a ‘‘breaking trinity’’ involving (i) the nonlocal wave-induced transport of momentum; (ii) the local wave-induced diffusion of momentum, heat, and tracers; and (iii) the local wave-induced transport of heat.While the authors’ formulation captures some of the important energy and momentum transfers between the grid-resolved flow and the gravity waves, their formulation is essentially incomplete in that it does not conserve energy. The inconsistencies are clear when the Z10 formulation is compared to that of Becker (2004, hereafter B04) and Shaw and Shepherd (2009, hereafter SS09), which do conserve energy. A comparison between the formulations is performed here in order to highlight the cause of the nonconservation in the Z10 formulation.