MJO Structure in the Superparameterized CAM

The Multi-scale Modeling Framework (MMF) has recently emerged as a unique approach toward bridging the gap between conventional global climate models (GCMs) and high-resolution global cloud-resolving models. The MMF replaces conventional cloud parameterizations with a small-domain cloud-resolving model (CRM; often called in this context a "super-parameterization"), embedded within each GCM grid column, to explicitly represent clouds and their effects. Recently, the Colorado State University MMF was used to conduct a 19- year Atmospheric Model Intercomparison Project (AMIP)-style simulation using observed SSTs and sea ice extent as the lower boundary conditions and the NCAR Community Atmosphere Model (CAM) as the host GCM. Highlights from a detailed examination of the MMF-simulated structure of intraseasonal convectively- coupled disturbances, i.e., the Madden-Julian Oscillation (MJO), will be presented. In the MMF simulation, the composite structure of MJO-like disturbances compares very favorably with the observed MJO based on reanalyses and satellite-derived measurements, although the magnitude of intraseasonal variability is slightly too strong in the model.