The Use of Reduced Complexity Frameworks for Model Development

The use of idealized modeling has had a long history in the understanding of the atmosphere. As global atmospheric models become more complex (i.e., higher resolution, improved parameterizations, higher-order dynamics packages), the use of idealized modeling for process studies remains as vital as ever. This work presents a hierarchy of reduced complexity testbeds that have been used to explore sensitivities of model design choices at reduced computational expense. The role of convective parameterizations at high horizontal resolution and their impacts on clouds, circulation, and precipitation processes are explored as they represent large uncertainties in current-generation model. The National Center for Atmospheric Research's Community Atmosphere Model 5 (CAM5) is configured in various configurations, including rotating and non-rotating radiative-convective equilibrium, to investigate the simulation of organized convection at next-generation horizontal resolutions. In particular, the ability of CAM5 to simulate tropical cyclones is a focal point of the work. At grid spacings of less than 30 km, the storm inner core is more intense and compact while the size of the outer circulation decreases only marginally compared to more traditional climate resolutions. Furthermore, precipitation extremes are shown to be particularly resolution dependent, especially in the non-rotating context.