Legacy of the Madden-Julian Oscillation Working Group
There is a long history of observational and model evaluation of the MJO. Even so, the underlying physics of the MJO remains poorly understood. Initial analyses of the MJO in models concentrated on large-scale diagnosis using such variables as velocity potential and/or zonal winds, and occasionally precipitation or outgoing longwave radiation. The first time a large number of models were systematically evaluated using a common set of diagnostics was in Slingo et al. (1996), who evaluated 15 general circulation models that were contributed to the Atmospheric Model Intercomparison Project (AMIP; Gates et al. 1992). However, the high- LLNL-TR-762421 frequency (daily) model data available to Slingo et al. (1996) were limited, and it was only with the advent of NWP-based reanalyses that a more comprehensive understanding of the 3-dimensional structure and the thermodynamics of the MJO became possible, thus helping to establish the variables relevant to the study of the MJO. International interest in the MJO began to blossom on the heels of the 2006 “Workshop on the Organization and Maintenance of Tropical Convection and the Madden Julian Oscillation,” held at the International Center for Theoretical Physics in Trieste, Italy. With its stated goals of understanding the influence of MJO in the context of the tropical circulation and its remote impacts, and discussion of future directions including the MJO impact on predictive capability, the time was right for a more coordinated attack on understanding and simulating the MJO.