The Madden-Julian Oscillation in General Circulation Models: An Analysis of Factors Relevant to Its Initiation, Maintenance, and Suppression

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The project will improve the modeling of intra-seasonal variability in climate models. The Madden-Julian Oscillation (MJO) is a key component of intra-seasonal variability, and plays a significant role in modulating circulation and precipitation variability in the global Tropics and subtropical regions. MJO also influences the Asian-Australian summer monsoons and possibly even ENSO variability. Current climate models are notably deficient in simulating MJO variability. Because of being sandwiched between two notable fluctuation time-scales-the shorter time-scale weather and the longer time-scale seasonal-to-interannual variability-MJO has not received significant research attention until recently. Drs. Randall, Demott and Khairoutdinov (all from Colorado State University) will investigate the initiation and evolution of MJO variability in a climate model in which clouds are resolved (and not parameterized). A cloud-resolving scheme will be implemented in the NCAR Community Climate System Model (CCSM). Project tasks will include refining this scheme, and ascertaining the sensitivity of MJO simulation to various aspects of the implementation. The PIs will develop a diagnostic analysis package targeting MJO variability, and make it available for community use through the CCSM web site.