Exploring a Uniformly-Rotating World in Global Radiative-Convective Equilibrium

Abstract:

A standard atmospheric general circulation model is set up in a uniformly-rotating global radiative-convective equilibrium configuration to explore the equilibrium state, including the statistics of its constituent tropical cyclones, and its sensitivity to horizontal resolution. The Community Atmosphere Model 5 (CAM5) is run at the conventional resolution of approximately 100 km grid spacing and a high-resolution of 25 km grid spacing globally. The setup utilizes an aquaplanet configuration with spatially-uniform, diurnally-varying insolation, uniform fixed sea surface temperatures and a uniform rotation rate equal to that at 10◦N. The resulting state is one in which tropical cyclones fill the global domain, such that storm count and outer storm size covary strongly. Despite significant changes in the statistics of storm count, intensity, and structure, the mean environment, including the potential intensity, is found to be nearly insensitive to resolution. Results are compared with the non-rotating case from a prior study, and a generalized conceptual framework for the interpretation of aggregation with or without rotation, as well as the respective sensitivity to model parameters, is proposed.