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David M. Zermeño-Díaz, Chidong Zhang, Pavlos Kollias, and Heike Kalesse

1. Introduction In the tropics, shallow cumulus clouds (herein called shallow clouds) are the most populous cloud type ( Lau and Wu 2003 ; Masunaga and Kummerow 2006 ) and produce about 20% of the total rainfall ( Short and Nakamura 2000 ). They are embryos for tropical deep convective disturbances in different time scales ( Mapes et al. 2006 ). Diabatic heating and moistening effects from shallow clouds have been suggested to be particularly important to the Madden–Julian oscillation (MJO

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Richard H. Johnson, Paul E. Ciesielski, James H. Ruppert Jr., and Masaki Katsumata

a. Sounding observations The DYNAMO sounding network was composed of two quadrilateral arrays—one north and one south of the equator—referred to as the northern and southern sounding arrays or NSA and SSA, respectively ( Fig. 1 ). Details of the sounding systems, observing characteristics, and quality-control procedures are contained in Ciesielski et al. (2014a) . Incorporated into our analyses are corrections for flow distortion and island heating effects by the mountainous island of Sri Lanka

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Ji-Hyun Oh, Xianan Jiang, Duane E. Waliser, Mitchell W. Moncrieff, Richard H. Johnson, and Paul Ciesielski

, it has been noted that the westerly wind events (WWEs) associated with the MJO can impact El Niño–Southern Oscillation (ENSO) ( Zhang 2005 ; Hendon et al. 2007 ; Seiki and Takayabu 2007 ). Despite considerable effort made toward improving the prediction skill of the MJO, critical challenges still remain for current general circulation models (GCMs) to more accurately represent the MJO and, in particular, its initiation over the IO. Dominated by seasonally changing monsoon flow, the IO is a

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Michael S. Pritchard and Christopher S. Bretherton

simulation and linearly interpolated to the model's internal calendar day. To limit effects of α to the equatorial zone, after synthesis of the full velocities U and from their spherical harmonic subcomponents on the global Gaussian grid, the hybrid auxiliary velocity is calculated as That is, transitions smoothly via a smooth Heaviside approximation in latitude ϕ from the vortically perturbed velocity field (equatorward of a critical latitude ϕ 0 ) to the actual velocity field (poleward of

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Douglas C. Stolz, Steven A. Rutledge, Weixin Xu, and Jeffrey R. Pierce

microphysical and dynamical evolution of convective clouds (e.g., Tao et al. 2012 ; Rosenfeld et al. 2014 ). Observations from the Indian Ocean Experiment (INDOEX; Ramanathan et al. 2001 ) identified a strong meridional gradient in aerosol concentration in the CIO (e.g., Satheesh et al. 1998 ; Moorthy and Saha 2000 ; Ramanathan et al. 2001 ) and a substantial seasonal cycle related to the changing large-scale flow patterns of the Asian monsoon ( Li and Ramanathan 2002 ). Plumes of continental aerosols

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Ji-Eun Kim, Chidong Zhang, George N. Kiladis, and Peter Bechtold

; Wang et al. 2015 ; Janiga and Zhang 2016 ; Wang et al. 2016 ). It was found that low-level moistening preceding the passage of the MJO is dominated by the effects of shallow precipitating clouds. Eddy transport by congestus and deep convective clouds contribute to subsequent mid- and upper-level moistening, respectively, as well as low-level drying. Nonprecipitating clouds mainly modulate the column-confined moisture tendency through their effects on radiation. Local surface evaporation

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Angela K. Rowe, Robert A. Houze Jr, Stacy Brodzik, and Manuel D. Zuluaga

dual-polarization capability of S-PolKa to determine whether the microphysical characteristics of the precipitation particles evolve in ways that are related to diurnal effects on the precipitation mechanisms at play in the MJO REs. It is important to note that it is possible for the diurnal cycle to affect the timing of the deep convective rain episodes on a 2-day time scale. Chen and Houze (1997) showed how the upper-level cloud shield of a mesoscale deep convective system over the warm

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Rachel C. Zelinsky, Chidong Zhang, and Chuntao Liu

the boreal winter and a secondary peak occurring in boreal summer ( Zhang and Dong 2004 ). About 50% of the MJO in both MJO groups (six for MJO_I and seven for MJO_NI) used in the study initiated during boreal summer months (May–September) ( Figs. 4e–h ). If there are seasonal effects in the following analysis, then it should be equal between the two MJO groups. The MJO events were not separated into seasonal groups due to the small sample size of events. In the rest of this section, comparisons

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H. Bellenger, R. Wilson, J. L. Davison, J. P. Duvel, W. Xu, F. Lott, and M. Katsumata

) that formed during the different experiments are indicated by the correspondingly colored dotted paths (see section 2d for details). Details on the number and frequencies of launches together with the type of radiosondes are given in Table 1 . In the cloud-free free atmosphere, turbulence occurs intermittently in the form of isolated and horizontally elongated patches (e.g., Wilson et al. 2005 ). The resulting effects of these intense and localized mixing events are difficult to evaluate

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Sharon L. Sessions, Stipo Sentić, and David J. Raymond

; saturation fraction, GMS, and MFI to be defined in the next section). To emphasize the relationship between the large-scale rotations and changes to atmospheric stability, compare the time series of the PV anomalies ( Fig. 5a ) and the instability index ( Fig. 5b ). During events (gray shading and bold lines), these are highly correlated, thus demonstrating the interplay between the dynamic and thermodynamic environments. Note that the seasonal trend in the increased PV anomalies (denoted with the red

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