Atmospheric meridional circulation as seen from a moist static energy perspective

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A major role of the atmosphere is to maintain relatively cold climate conditions in the Tropics and relatively warm climate conditions at the Poles. This aspect of the atmospheric circulation can be envisioned as a gigantic (planetary thermodynamic machine importing low energy air to low latitudes and exporting high energy air to high latitudes. Although this is a very basic aspect of climate, there is to date no theory to predict what the intensity of this mass exchange from low to hig latitudes is, nor is there a theory to predict the energy of the air that is being carried poleward and equatorward by the atmospheric circulation. This proposal aims at investing at depth the mechanisms controlling both topics. Such effort is crucial to obtain an accurate prediction of the change in poleward energy transport of the atmosphere and surface temperature arising either because of natural fluctuations, or in response to anthropogenic forcing. To tackle these problems, we put forward the following key working hypotheses: (i) the energy of the air carried both poleward and equatorward can be predicted from the surface temperature, itself largely controlled by large scale ocean-atmosphere interactions. (ii) the intensity of the atmospheric mass transport is a simple function of the intensity of radiative cooling and the equator to pole surface temperature gradient. The most novel aspect of this proposal is to test these hypotheses against observational datasets AND simple climate model simulations run in idealized geometries.