Compensation of Hemispheric Albedo Asymmetries by Shifts of the ITCZ and Tropical Clouds

摘要: Despite a substantial hemispheric asymmetry in clear-sky albedo, observations of Earth’s radiation budget reveal that the two hemispheres have same all-sky albedo. Here, aquaplanet simulations with atmosphere general circulation model ECHAM6 coupled to slab ocean are performed study what extent and by which mechanisms clouds compensate asymmetries Clouds adapt imposed because intertropical convergence zone (ITCZ) shifts into dark surface hemisphere. The strength this tropical compensation mechanism is linked magnitude ITCZ shift. In some cases shift so strong as overcompensate yielding range climates for hemisphere lower albedo has higher sensitive convection scheme depth ocean. Cloud–radiative feedbacks explain part sensitivity they amplify Tiedtke (TTT) but neutral effect Nordeng (TNT) scheme. A shallower depth, thereby reduced thermal inertia underlying increased seasonal cycle, stabilizes against annual-mean shifts. results lend support idea climate system adjusts minimize asymmetries, although there no indication must exactly