On the Hemispheric symmetry of the Earth's Energy Balance (Invited Presentation)

Abstract: Perturbations to the Earth's energy balance force climate change. The latitudinal variation of the energy balance establishes regional climate zones through its influence on the atmospheric and ocean circulations that, in turn, move heat poleward. We currently lack a quantitative understanding of how this energy balance and the poleward energy transport adjust to different forcings that determine climate change and no constraint exists to guide this understanding in either observations of models. Here we show that the Earth's energy balance exhibits a remarkable symmetry about the equator, and that this symmetry is fundamentally a consequence of the fact that there is zero heat transport across the equator. Our analysis points to clouds as the principal agent that regulates the energy balance and sets the symmetry. The lack of such symmetry in models will be examined and the consequence of this lack of symmetry is addressed in a connected presentation by J.Haywood.