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Ian Folkins, S. Fueglistaler, G. Lesins, and T. Mitovski

1. Introduction In the tropics, convective clouds are often considered to fall into one of three categories: boundary layer, shallow, or deep ( Johnson et al. 1999 ). Boundary layer convective clouds contribute to an upward eddy flux of heat and moisture from the surface, are usually nonprecipitating, and rarely penetrate the 2-km local maximum in static stability. Most of the rainfall in the tropics is associated with deep cumulonimbus and stratiform clouds, whose outflow is preferentially

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Xiping Zeng, Wei-Kuo Tao, Toshihisa Matsui, Shaocheng Xie, Stephen Lang, Minghua Zhang, David O’C Starr, and Xiaowen Li

, have been observed to be more frequent in the tropics than in middle latitudes (e.g., Heymsfield et al. 1978 ; Wei et al. 1998 ; Igau et al. 1999 ). Zipser (2003) , after reviewing the aircraft observations from over the past decades, concluded that undilute updraft cores have not been found in the tropics but are common in severe storms in middle latitudes. Based on this meridional variation in fine cloud dynamic structure, it is inferred that the IE factor in the tropics is much larger than

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Hye-Yeong Chun, Jung-Suk Goh, In-Sun Song, and Lucrezia Ricciardulli

( c ) were carried out. It was found that on a global scale in the Tropics DCH has a dominant period of 1 day and a zonal wavelength of about 1600 km. The phase-speed spectrum of DCH is Gaussian type and its power decreases rapidly as phase speed increases from the maximal value at c = 0. This convective source spectrum is similar to that proposed by Beres et al. (2004) and SC05 for the cloud-top momentum flux formulations of convective GWD parameterizations. Two-dimensional ( k − ω

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R. B. Smith, P. Schafer, D. J. Kirshbaum, and E. Regina

(2006) , and Rotunno and Houze (2007) , among others], but almost all these studies have been in midlatitudes. A common element of previous studies is that orographic precipitation events were forced, either by a weather disturbance that is already precipitating, (e.g., frontal cyclone, squall line, easterly wave, or hurricane) or by the diurnal cycle of solar heating. We have two objectives: (i) to examine the physics of orographic precipitation in the tropics and (ii) to identify a location with

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Daniel J. Kirshbaum and Ronald B. Smith

). Orography also triggers moist convection by forcing conditionally unstable air to rise over a mountain massif, which is commonly observed in midlatitutes along the west coast of North America (e.g., Kirshbaum and Durran 2005 ), the southern Andes ( Smith and Evans 2007 ), and the Cévennes Vivarais region of France (e.g., Anquetin et al. 2003 ), among other locations. This mechanism also operates in the tropics when trade wind flow encounters mountainous terrain, which can occur along a continental

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Chidong Zhang and Samson M. Hagos

is central to the study of the large-scale circulation in the tropics and its interaction with moist convection. Previous studies on the role of heating profiles in the large-scale circulation used either observed heating profiles of mesoscale convective systems (e.g., Mapes and Houze 1995 ; Schumacher et al. 2004 ) or idealized profiles for large-scale diabatic heating (e.g., Geisler 1981 ; Hartmann et al. 1984 ; Wu et al. 2000 ). Our knowledge of large-scale heating structures and

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Richard S. Lindzen

156 JOURNAL OF THE ATMOSPHERIC SCIENCES VoLuta~.31Wave-CISK in the Tropics RICItARD S. [~INDZEN1Center for Earth and Planetary Physics, Harvard University, Cambridge, Mass. 02138(Manuscript received 7 June 1973, in revised form 10 September 1973) ABSTRACTCISK (Conditional Instability of the Second Kind) is examined for internal waves where low-level convergence is

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Michiya Hayashi and Hisanori Itoh

). The TA has no serious problem in the midlatitude. However, some studies have suggested that near the equator where the factor cosine is large, this approximation may not be appropriate. For example, WB95 used a scale analysis to indicate that, since diabatic heating due to cumulus convection involves air mass ascent in the tropics, the NCT associated with vertical motions in the zonal momentum equation may become too large to be neglected. WB95 also implied that in the perturbation form of the

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Andrew J. Majda and Rupert Klein

horizontal temperature gradients in the equatorial middle troposphere are weak in various flow regimes formally yields simplified equatorial balanced dynamics ( Charney 1963 ; Held and Hoskins 1985 ; Browning et al. 2000 ). There has been a recent surge of activity in developing and utilizing such balanced weak temperature gradient (WTG) approximations in the Tropics and subtropics with horizontal advection of moisture included in order to model the regions of surface precipitation and their

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Patrick C. Taylor

associated thermodynamic and dynamic characteristics. This demonstration of subseasonal variability of the convective diurnal cycle motivates this analysis of variability in the monthly TOA flux diurnal cycle in the tropics. The spatial domain is restricted to the tropics, defined as 30°N–30°S, to focus on regions with large, and persistent diurnal cycle signals. The monthly-mean diurnal cycle is defined as the composite of hourly or 3-hourly TOA fluxes over a single month using the Clouds and the Earth

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