GCM tests of theories for eddy heat transport in the atmosphere

A series of numerical experiments were carried out in a full-physics atmospheric GCM to test parameterisations of eddy heat flux based on flux-gradient relations. The length and temperature scales of atmospheric motions were varied by changing external parameters, including the radius of the earth, planetary rotation rate, meridional gradient of sea surface temperature, and radiative forcing. It was found that the correlation between eddy velocity and temperature perturbations is constant over a wide range of conditions. The temperature perturbations scale with the Rhines beta scale, multiplied by the horizontal temperature gradient. The eddy velocity correlates well with a new scaling, that assumes the efficiency of the atmospheric heat engine is constant and uses a turbulence relation valid in an inertial range. Combining these results gives a parameterisation that accurately predicts the eddy heat fluxes diagnosed in the GCM.