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Christopher C. Walker and Tapio Schneider

Hadley circulation. Since a substantial fraction of the isentropic mass flux of the Hadley circulation does not recirculate within the Tropics but connects continuously to the extratropical isentropic mass fluxes to form overturning circulations that span hemispheres ( Fig. 1 ), it is possible that the baroclinic eddies that effect the extratropical mass fluxes influence the Hadley circulation. Indeed, the Hadley circulation in axisymmetric models with hemispherically symmetric thermal driving is

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Dargan M. W. Frierson

better simulation of the climate over wide parameter ranges. For instance, we have recently used the SBM scheme in a study of the dynamics of Titan’s methane clouds ( Mitchell et al. 2006 ). In this paper, the model of Frierson et al. (2006) with the SBM convection scheme serves an effective intermediate complexity context in which to evaluate the importance of moisture on the tropical general circulation. We show in this study that the parameterization of moist convection can have a significant

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Ana P. Barros, Olivier P. Prat, Prabhakar Shrestha, Firat Y. Testik, and Larry F. Bliven

drop was able to dissipate the energy without breakup. 5. Conclusions A comparative study of recent laboratory experiments of raindrop breakup against previous results by LL82a , LL82b , and ML75 was presented. The experimental fragment size distributions (FSD) for selected drop pairs (DL–DS) were evaluated against explicit simulations using a dynamical microphysics model ( PB07a ; PB07b ) that uses breakup functions (kernels) based on LL82a , LL82b , and MF04 . The main results of the

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Hai Lin, Gilbert Brunet, and Jacques Derome

indications of extratropical forcing, it is still unclear how the MJO is excited and maintained. Using a linear two-level model with a realistic three-dimensional basic-state flow and a cumulus convection parameterization, Frederiksen and Frederiksen (1997 , hereafter FF ) found that one of the unstable modes couples the extratropics with a tropical 40–60-day disturbance, which is similar to the MJO. The connection of the MJO to the extratropical instability was also suggested by Straus and Lindzen

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Stephanie Leroux and Nicholas M. J. Hall

AEJ through a barotropic/baroclinic instability mechanism. This instability hypothesis appears to be supported by the results of several idealized modeling studies (e.g., Rennick 1976 ; Simmons 1977 ; Mass 1979 ; Thorncroft and Hoskins 1994a , b ; Paradis et al. 1995 ; Thorncroft 1995 ; Grist et al. 2002 ) showing realistic easterly wave structures growing on various unstable zonally uniform jets. Hall et al. (2006) give a summary of the different zonal jets used as basic states in a

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Robert Pincus and K. Franklin Evans

. First, specifying the problem can be quite difficult because this requires describing the instantaneous distribution of extinction, single-scattering albedo, and scattering phase function in three spatial dimensions at very small scales. No current observing system is up to this task, although finescale cloud models can provide useful test cases. Second, solving the three-dimensional radiative transfer equation is much more computationally expensive than solving its one-dimensional counterpart

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Andreas Müller and Volkmar Wirth

underlying the observed TIL are not well understood. Modeling studies such as those of Wirth and Szabo (2007) or Son and Polvani (2007) suggest that its formation may be due to conservative dry dynamics. Alternatively, Randel et al. (2007) argued that radiative effects associated with water vapor and ozone should play an important role. Further potentially important mechanisms involve gravity waves, turbulence, deep convection, and the Brewer–Dobson circulation. The degree to which any of these

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Gilles Bellon and Adam Sobel

and Li 2005 ; Wang et al. 2006 ), these propagating disturbances exhibit a high degree of zonal symmetry within a particular longitude band. Zonally symmetric models have therefore been used to improve our understanding of the 30–60-day mode ( Webster and Chou 1980 ; Webster 1983 ; Goswami and Shukla 1984 ; Gadgil and Srinivasan 1990 ; Srinivasan et al. 1993 ; Nanjundiah et al. 1992 ; Jiang et al. 2004 ; Bellon and Srinivasan 2006 ; Drbohlav and Wang 2005 ). In a similar way that the

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Kazuyuki Miyazaki and Toshiki Iwasaki

methods in expressing mean and eddy transport terms, and the analysis describes the formation and decay mechanisms controlling the gradient of the trace species. The trace species considered in this study is global nitrous oxide (N 2 O), for which data were obtained from a global chemical transport model and were used as a tracer in the gradient genesis analysis. Two-dimensional (2D) model results revealed the roles of the mean meridional circulation in the genesis of the gradient. 2. Data Data used

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Giacomo Masato, Brian J. Hoskins, and Tim J. Woollings

between a block and a synoptic ridge purely semantic? The aim of this note is to address this question by comparing observations of blocking with the output from a first-order Markov model, as suggested by Tyrlis and Hoskins (2008a , hereafter TH08a ). Such a model is the simplest possible statistical red noise model, and yet many of the characteristics of transient synoptic-scale eddies can be well modeled by such a process ( Branstator 1995 ; Whitaker and Sardeshmukh 1998 ). If the observed

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