Self-organization of convection and regulation of tropical climate

Imparte: Marat Khairoutdinov, School of Marine and Atmospheric Sciences, Stony Brook University

E

vidence from paleoclimate reconstructions suggests that the tropical climate has been essentially stable with just a few degrees variations in SSTs despite much higher concentration of greenhouse gases than at present. It has been hypothesized that the tropical climate is maintained by self-aggregation or clustering of convection. Idealized cloud-resolving simulations show that warmer SSTs are conducive to aggregation, which has a tendency to dry out the atmosphere reducing the greenhouse effect and, hence, providing powerful negative feedback to warming. Similar mechanism can also operate in response to projected climate warming due to anthropogenic forcing. Some recent results of radiating-convective equilibrium over equatorially centered planetary scale channel on aqua-planet using a cloud-resolving model will be presented, including simulated MJOa and its sensitivities, and also convective cluster statistics as compared to satellite observations of Tropics. The results of global cloud-resolving simulations of Earth using a newly developed global cloud-resolving model at 4 km grid spacing will be also discussed.