The Curious Nature of the Hemispheric Symmetry of the Earth’s Water and Energy Balances

This paper presents new estimates of the hemispheric energy balance based on an assembly of radiative flux and ocean heat data. Further, it provides an overview of recent simulations with fully coupled climate models to investigate the role of its representation in causing tropical precipitation biases. The energy balance portrayed here features a small hemispheric imbalance with slightly more energy being absorbed by the Southern hemisphere. This yields a net transport of heat towards the NH composing of a northward cross-equatorial heat transport by the oceans and a southward heat flow in the atmosphere. The turbulent fluxes and hemispheric precipitation balance to about 3 Wm −2 with slightly larger total accumulation occurring in the NH. CloudSat data indicate more frequent precipitation in the SH implying more intense precipitation in the NH. Fully coupled climate model simulations show that reducing hemispheric energy balance biases does little to reduce existing biases in tropical precipitation.