Self-aggregation in a cloud resolving model

Several studies using high-resolution cloud resolving models point out the tendency of atmospheric convection to self-aggregate. This self-aggregated state is a spatially organized atmosphere composed of two large areas: a moist area with intense convection, and a dry area with strong radiative cooling. Whether or not a horizontally homogeneous convecting atmosphere self-aggregates depends on various parameters in the model. A recent study in 3D points out the importance of convection-water vapor-radiation feedbacks, and notes that self-aggregation only occurs on large domains. Currently, there is no theory to explain this dependence on domain size. We will investigate the onset of self-aggregation for a large range of domain sizes and resolutions. Of particular interest is the impact of self-aggregation on atmospheric properties at very high resolutions. The large changes in the means climate state and radiative fluxes accompanying self-aggregation raise questions as to what simulations at lower resolutions with parameterized convection, in similar homogeneous geometries, should be expected to produce to be considered successful in mimicking a cloud-resolving model.