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Kunio Yoneyama, Chidong Zhang, and Charles N. Long

is the only large tropical ocean that is bounded by land in three directions. It is therefore the ocean that experiences the strongest influence of the monsoons. The monsoon circulation and the trade winds over the Indian Ocean induce unusually shallow thermocline in the middle of the basin, known as the Seychelles–Chagos thermocline ridge ( Vialard et al. 2009 ), and strong eastward surface current along the equator, the Wyrtki jet, which appears semiannually during the monsoon transition

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James N. Moum, Simon P. de Szoeke, William D. Smyth, James B. Edson, H. Langley DeWitt, Aurélie J. Moulin, Elizabeth J. Thompson, Christopher J. Zappa, Steven A. Rutledge, Richard H. Johnson, and Christopher W. Fairall

fundamental understanding, because of lack of adequate measurements. The contribution of atmosphere–ocean feedbacks to the emergence and evolution of the MJO remains unknown. This notion prompted the Dynamics of the Madden–Julian oscillation (DYNAMO; ) hypothesis III ( Yoneyama et al., 2013 ): The barrier layer, wind- and shear-driven mixing, shallow thermocline, and mixing-layer entrainment all play essential roles in MJO initiation in the Indian Ocean by controlling

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James H. Ruppert Jr. and Richard H. Johnson

Littoral Air–Sea Processes (LASP) ( Yoneyama et al. 2013 ; Zhang et al. 2013 ). Herein, these efforts will be referred to collectively as DYNAMO. Two MJO events were comprehensively sampled in DYNAMO, providing an unprecedented opportunity to diagnose the key processes during the transition from shallow to deep convection in the MJO. The MJO is a zonal overturning circulation that propagates eastward across the tropics at ~5 m s −1 in connection with an upper-level divergent wind pattern, which

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

mixed layer overnight, the daily-mean SST is higher than it would have been in its absence ( Shinoda 2005 ; Mujumdar et al. 2011 ). In a coupled ocean–atmosphere general circulation model (GCM), this rectification of daily-mean SST by the diurnal variability of SST can increase the long-term-mean SST by 0.2°–0.3°C ( Bernie et al. 2008 ), with a subsequent improvement in the mean precipitation. In their simulations, the MJO is also improved, resulting from the increase in intraseasonal SST

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Xiouhua Fu, Wanqiu Wang, June-Yi Lee, Bin Wang, Kazuyoshi Kikuchi, Jingwei Xu, Juan Li, and Scott Weaver

1. Introduction The Madden–Julian oscillation (MJO) is a dominant mode of tropical convection variability on intraseasonal time scales ( Madden and Julian 1971 ; Zhang 2005 ; Lau and Waliser 2011 ). The MJO convective envelope usually initiates over equatorial Africa and the western equatorial Indian Ocean ( Wang and Rui 1990a ). The associated circulation systems propagate eastward as a Kelvin–Rossby wave couplet ( Wang 1988a ; Wang and Rui 1990b ; Hendon and Salby 1994 ; Roundy 2012

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Hyodae Seo, Aneesh C. Subramanian, Arthur J. Miller, and Nicholas R. Cavanaugh

exerts a profound influence on global weather and climate ( Zhang 2005 , 2013 ), the complexities of multiscale interaction of the circumequatorial tropical atmospheric circulation with individual cloud systems and upper-ocean processes make it difficult for the climate models to accurately represent the MJO (e.g., Zhang 2005 ; Madden and Julian 2005 ; Lin et al. 2006 ; Hung et al. 2013 ). Despite recent advancements in MJO simulation and prediction in climate and forecast models (e

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

1987 ) or boundary layer frictional wave-CISK (e.g., Wang and Rui 1990 ; Salby et al. 1994 )] or by a quasi-equilibrium between circulation and radiative-convective equilibrium ( Neelin et al. 1987 ; Emanuel 1987 ; Neelin and Zeng 2000 ). Other models with nonlinear interaction of smaller-scale waves (e.g., through triggering convection) predict organization of synoptic-scale convection into a large MJO envelope ( Majda and Stechmann 2009 ; Yang and Ingersoll 2013 ). The waves predicted by

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Weixin Xu, Steven A. Rutledge, Courtney Schumacher, and Masaki Katsumata

variability (as a function of MJO phase) within the ridge is greater than outside the ridge. This SST ridge is consistent with the presence of the Seychelles–Chagos thermocline ridge ( Vialard et al. 2008 ) in the central IO. Increases in SST over the equatorial IO preceded the rainfall maxima there ( Fig. 2 ) by one to two phases. For example, SSTs over the DYNAMO region began increasing starting from the most suppressed phase (phase 6; Fig. 5f ), peaking one phase prior to the active MJO period (phase

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Richard H. Johnson and Paul E. Ciesielski

convective activity throughout the life cycle of the MJO. Surface, sounding, and radar measurements collected during DYNAMO have shed new light on properties of the boundary layer and lower troposphere from the suppressed to active phases of the MJO. During suppressed periods, boundary layer circulations frequently developed that brought about organized roll and cellular patterns of shallow convection and played a role in lower-tropospheric moistening ( Bellenger et al. 2015 ; Rowe and Houze 2015

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Kacie E. Hoover, John R. Mecikalski, Timothy J. Lang, Xuanli Li, Tyler J. Castillo, and Themis Chronis

central and eastern Pacific Ocean. During the October event, there were very little effects from the austral summer monsoon circulation along with a persistent zonally flat thermocline for much of October and November. The ITCZ was positioned south of the equator over the Indian Ocean, as is typical for boreal winter, and strong equatorial westerlies were set up during December and into January ( Gottschalck et al. 2013 ). For a more in-depth overview of the entire DYNAMO project, the reader is

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