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George H. Bryan, Jason C. Knievel, and Matthew D. Parker

counteracts the cold pool’s tendency to sweep environmental air over the top of the cold pool. An optimal state exists wherein the shear approximately balances the cold pool’s circulation, leading to the deepest lifting of environmental air. Extending the theory to more complex squall lines, RKW88 argued that lifting at the leading edge of cold pools is an essential element in squall lines, because it generates new convective cells. Thus, RKW88 concluded that the combination of the relative effects of

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Peter S. Dailey and Robert G. Fovell

1. Introduction The sea-breeze circulation (SBC) is a mesoscale phenomenon driven by daytime heating contrasts between land and water surfaces and a subject of long-standing interest (e.g., Davis et al. 1890 ). It has been observed with a variety of tools including aircraft measurements (e.g., Hatcher and Sawyer 1947 ; Fisher 1960 ; Reible et al. 1993 ), pilot balloons (e.g., Frizzola and Fisher 1963 ; Yoshikado 1990 ), satellite imagery (e.g., Wakimoto and Atkins 1994

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Bjorn Stevens, Chin-Hoh Moeng, Andrew S. Ackerman, Christopher S. Bretherton, Andreas Chlond, Stephan de Roode, James Edwards, Jean-Christophe Golaz, Hongli Jiang, Marat Khairoutdinov, Michael P. Kirkpatrick, David C. Lewellen, Adrian Lock, Frank Müller, David E. Stevens, Eoin Whelan, and Ping Zhu

phrase “fact gap” to describe this state of affairs, a gap which some (e.g., Wyngaard 1998 ) believe is widening. In the absence of decisive measurements the principal method of evaluating LES has been through exhaustive sensitivity studies of individual models and comparisons among many models. The hope is that the robustness of the method testifies to its fidelity. For the most part such studies have cast a favorable light on LES. However, a couple of studies (e.g., Moeng et al. 1996 ; Stevens

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Corey K. Potvin, Alan Shapiro, Tian-You Yu, Jidong Gao, and Ming Xue

linear spatial model ( Smith and Elmore 2004 ). This method produces more accurate estimates of shear than methods that rely upon point-to-point velocity measurements. Fuzzy-logic approaches (e.g., Wang et al. 2008 ) acknowledge the typically large overlap between the probability distribution functions of parameters used in vortex detection techniques, as opposed to binary methods that use rigid thresholds to make detection decisions. Liu et al. (2007) proposed a preliminary tornado detection

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Yubao Liu, Da-Lin Zhang, and M. K. Yau

use of high resolutions and sophisticated microphysics parameterizations to model properly the structures of these tropical storms. The measurements also provide the ground truth for verifying the performance of numerical models. From the above review, it is clear that the previous hurricane models are limited in one or more of the following aspects: balance approximation, axisymmetric assumption, low resolution, hydrostatic dynamics, crude physical parameterizations, idealized initial conditions

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Nolan T. Atkins, Roger M. Wakimoto, and Tammy M. Weckwerth

, respectvely.1. Introduction The sea-breeze circulation is one of the most extensively studied mesoscale meteorological phenomenon,with a history dating back to the seventeenth century(lelm 1973'). A myriad of theoretical and observationalstudies have emerged since World War II clarifying theunderlying physics and general kinematic and thermodynamic structure of the circulation [ see Atkinson(1981) for a review]. Its effects on coastal meteorology such as air pollution transport (e.g., Mizuma andKalmta

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Stanley David Gedzelman and Robert A. Rilling

-levdstratification .is associated with larger amplitude surface pressure perturbations. The surface wave amplitudes are also highly dependent on the height ofwa~e generation, the state of development of thewaves and other nonlinear effects. Despite these andother complicating factors the fact remains that inan atmosphere which, is dynamically unstable, preexJ[sting disturbances are likely to be amplified. Fig. 3 contains a plot of observed wave amplitudesversus the minimum Richardson number in the sounding. The

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Seon Ki Park and Kelvin K. Droegemeier

), cloud water ( Q c ) and rainwater ( Q r ), and turbulent kinetic energy. (Ice processes are neglected in our study.) The advective modes are computed on big time steps with the leapfrog scheme and second-order centered space differencing, whereas the acoustic modes are integrated on small time steps with an implicit scheme. We operate the model in a very simple mode using only Kessler explicit warm-rain microphysics ( Kessler 1969 ). An extensive description of the model can be found in Xue et al

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A. Bellucci, S. Masina, P. DiPietro, and A. Navarra

intense and extending far too west, compared to the Reverdin climatology. The effects of data assimilation on subsurface zonal currents is now inspected by comparing the analysis and control experiment results with climatological profiles from TAO acoustic Doppler profiler (ADCP) observations for the 1992–2001 period, at two locations in the western and eastern equatorial Pacific. In the eastern Pacific (0°, 110°W; Fig. 8 , right panel) both the control and the analysis exhibit a westward bias. This

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C. Emersic, P. L. Heinselman, D. R. MacGorman, and E. C. Bruning

folded the screening-layer charge into the cloud interior to interact with a charge rising in the updraft and thereby to produce electric field magnitudes large enough to cause lightning. Such a possibility is supported by the observations of Blythe et al. (1988) and Stith (1992) , who used tracers to show that the upper cloud boundary is entrained into the upper cloud. Polarimetric radar data or in situ measurements may be needed to shed more light on this phenomenon. b. Cloud-to-ground lightning

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