Lorenz's global energy cycle includes the conversion rate C between available potential and kinetic energy. In traditional estimates of C only gridscale processes were evaluated; subgridscale processes were lumped into dissipation. It is argued that this is inadequate; organized subgridscale heat fluxes like deep convection cannot be treated as molecular.
Here both Cgrid and Csub are evaluated from the ECMWF Integrated Forecast System, for a 1-yr forecast in climate mode. The subgridscale fluxes are obtained from the model parametrization and the results tested for consistency; the largest contribution comes from the convection scheme. The integrand of Csub, the familiar ‘buoyancy flux’, is locally much smaller than its gridscale counterpart . However, the buoyancy flux is upward throughout, and thus representative for, the global atmosphere. The global annual means are Cgrid= (3.4 ± 0.1) W m−2 and Csub= (1.7 ± 0.1) W m−2. Further, the gridscale generation rate of available potential energy is evaluated independently and found to be Ggrid= (3.0 ± 0.2) W m−2.
These results suggest that (i) the subgridscale processes contribute significantly to the Lorenz energy cycle and (ii) the cycle, represented by the total dissipation of D= (5.1 ± 0.2) W m−2, is more intense than all earlier gridscale estimates have indicated.