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M. R. Turner and J. Norbury

system need to be added back into the system in an “averaged” sense via parameterizations of the subgrid-scale behavior. An important subgrid-scale phenomenon that needs parameterizing in this way is moist cumulus convection ( Arakawa 2004 ). This phenomenon plays a significant role in the vertical fluxes of entropy, air mass, moisture and air momentum in the atmosphere, each of which can have large magnitudes. This is particularly the case in the tropical regions of Earth’s atmosphere where these

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Usama M. Anber, Scott E. Giangrande, Leo J. Donner, and Michael P. Jensen

1. Introduction Modern climate science inferred from global climate models (GCMs), as well as observations, points toward the important influence by cumulus convection on the vertical structure of the atmosphere. Through vertical distribution of heat, moisture, and momentum, cumulus convection determines precipitation and clouds, and largely affects the global energy balance through interaction with the solar and longwave radiation. State-of the-art climate and numerical weather prediction (NWP

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Peter Bechtold, Noureddine Semane, Philippe Lopez, Jean-Pierre Chaboureau, Anton Beljaars, and Niels Bormann

1. Introduction Equilibrium convection is generally interpreted as indicating that the convection is in equilibrium with the forcing due to the mean advection and processes other than convection. In other words, the convection can react on time scales short enough for the residual tendency between the forcing and the convective stabilization to be small as measured by some function such as the cloud work function or the convective available potential energy (CAPE) ( Arakawa and Schubert 1974

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David M. Romps and Zhiming Kuang

first defined for convection by Stull (1984) [see also the review by Stull (1993) ]. As originally defined, the element b ij is proportional to the mass of air transported from z j at t = 0 to z i at t = Δ t (per infinitesimal intervals around z i and z j ). As such, is a function of the time interval Δ t . In a numerical simulation, b ij is easily diagnosed using a “set-and-go” method with tracers: initialize a horizontally uniform tracer q j at t = 0 in the layer

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Olivier M. Pauluis and Agnieszka A. Mrowiec

1. Introduction Atmospheric convection transports energy and water from Earth's surface to the free troposphere. The ascent of warm, moist air in saturated turbulent plumes is balanced by subsidence of drier and colder air that takes place in the environment or in convective or mesoscale downdrafts. Convective systems, however, rarely occur as simple overturning cells; rather, they are associated with a variety of turbulent motions over a wide range of scales. Any analysis of such flow is

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Cathy Hohenegger and Bjorn Stevens

Using satellite observations and large-eddy simulations of the development of deep moist convection over the tropics, Hohenegger and Stevens (2013) argued that the moistening of the atmosphere by congestus clouds is too slow to explain the observed fast transition times, from congestus to cumulonimbus. Schultz (2013) wondered whether this result remains valid for the midlatitudes. Although a full analysis as performed in Hohenegger and Stevens (2013) has not been conducted for the

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Juliana Dias and Olivier Pauluis

the effect of convection on the large-scale circulation is to reduce the effective static stability of the atmosphere. Building on this approach, Frierson et al. (2004 , hereafter FMP) developed an idealized framework to study the feedback between water vapor and large-scale circulation that allows for interactions between precipitating and nonprecipitating regions. The model by FMP has been previously used to study the propagation of precipitating regions ( Stechmann and Majda 2006

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Roger M. Wakimoto and Hanne V. Murphey

1. Introduction One of the major challenges during the summer months is predicting the initiation of deep, moist convection ( Olsen et al. 1995 ; Fritsch and Carbone 2004 ). Forecasters often have difficulty assessing, under weak synoptically forced conditions, the potential of rising parcels of air to reach the level of free convection (LFC) and then maintaining positive buoyancy as they pass this level. Improvements in these short-term forecasts, however, resulted when organized lines of

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Claudia Pasquero and Eli Tziperman

1. Introduction Ocean general circulation model (GCM) equations are written for the gridbox-averaged quantities, and the subgrid-scale variability of temperature, salinity, and velocities is often parameterized in the form of eddy viscosity and diffusivity. Observations in regions of deep oceanic convection, such as the Labrador Sea, show that temperature T and salinity S fields have small- and mesoscale variability ( Lilly et al. 2003 ), which is believed to play an important role in the

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Fuqing Zhang and Jason A. Sippel

only modulated by the larger-scale environment ( Holland 1997 ; Willoughby 1999 ; Emanuel 1999 ). Upscale growth of moist convection, such as in the form of vortical hot towers (VHTs), may play a critical role in internal dynamics ( Hendricks et al. 2004 ; Krishnamurti et al. 2005 ; Montgomery et al. 2006 ). Therefore, limited predictability of moist convection may also ultimately limit the predictability of tropical cyclones, as is the case for extratropical cyclones ( Zhang et al. 2002

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