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  • DYNAMO/CINDY/AMIE/LASP: Processes, Dynamics, and Prediction of MJO Initiation x
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Tim Li, Chongbo Zhao, Pang-chi Hsu, and Tomoe Nasuno

radiation (OLR), confirmed the planetary scale of the MJO ( Weickmann 1983 ; Murakami and Nakazawa 1985 ; Lau and Chan 1986 ; Li and Zhou 2009 ). Studies also show that the oscillation is more broadband than the original 40–50-day period identified by Madden and Julian (1971) and can span a range of 20–100 days (e.g., Krishnamurti and Subrahmanyam 1982 ; Annamalai and Slingo 2001 ; Lau and Waliser 2005 ; Zhang 2005 ; Li and Wang 2005 , Waliser 2006 ). As the most significant variability

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Simon P. de Szoeke, James B. Edson, June R. Marion, Christopher W. Fairall, and Ludovic Bariteau

wave-CISK propagate faster than the MJO, and the shortest waves are the most unstable to wave-CISK ( Hendon 2005 ). Frictional wave-CISK predicts slower waves destabilized by boundary layer moist static energy convergence. Convectively coupled equatorial Kelvin, Rossby, and inertia–gravity waves are observed with higher frequencies and smaller scales that do not match the planetary scale of the MJO ( Wheeler and Kiladis 1999 ). Quasi-equilibrium models assume that latent heating above precipitation

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Kai-Chih Tseng, Chung-Hsiung Sui, and Tim Li

wave dynamics with a wave–conditional instability of the second kind (wave-CISK)-type parameterization of convective heating (e.g., Lau and Peng 1987 ). The most unstable wave in such a simplified system is normally at a small wavelength, which is different from the observed planetary-scale circulation associated with MJOs. To remedy the scale selection problem, Wang (1988) and Wang and Li (1994) added friction-induced boundary layer convergence in the wave-CISK framework. In the wave

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Simon P. de Szoeke and Eric D. Maloney

planetary-scale intraseasonal convective anomalies. Among many possible positive feedbacks, surface fluxes have been proposed to destabilize the atmosphere to the MJO ( Krishnamurti et al. 1988 ; Maloney and Sobel 2004 ). An early theory for the MJO proposed wind-induced surface heat exchange as important for MJO destabilization and propagation ( Emanuel 1987 ; Neelin et al. 1987 ). Forcing an atmospheric model with fluxes due to strong SST anomalies enhances its intraseasonal convection (e

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Adrian J. Matthews, Dariusz B. Baranowski, Karen J. Heywood, Piotr J. Flatau, and Sunke Schmidtko

diurnal warm layer and the state of the MJO is certainly not a perfect one. Convection and related conditions at a single geographical point (the glider location) are subject to large variability, as the planetary-scale MJO envelope is made up of contributions from multiple scales. This can clearly be seen in the time series of precipitation, wind speed, and shortwave radiation at the glider location ( Fig. 2b ). The tendency for wet, windy, and cloudy conditions in the active MJO stage and for dry

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Samson M. Hagos, Zhe Feng, Casey D. Burleyson, Chun Zhao, Matus N. Martini, and Larry K. Berg

precipitation associated with the two MJO episodes varies significantly from simulation to simulation. The CPM ( Fig. 2b ) captures the eastward propagation, but precipitation is generally overestimated during both the active and suppressed phases of the MJO. The simulation with the SAS cumulus scheme ( Fig. 2d ) also captures the eastward-propagating waves, and, in agreement with the observations, its precipitation during the suppressed phase is quite weak. The eastward propagations in the WRF simulations

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