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Andrew J. Heymsfield, Aaron Bansemer, Gerald Heymsfield, and Alexandre O. Fierro

1. Introduction Cirrus clouds at a given time cover about 20% of tropical latitudes and contribute significantly to regional and global radiation budgets ( Rossow and Schiffer 1999 ). Optically thick tropical cirrus are produced primarily through deep convection and generate as much as 25% of the earth’s net cloud radiative forcing ( Hartmann et al. 1992 ). The primary impact of thin versus thick cirrus is on the shortwave energy budget, and the albedo of these ice clouds depends on their

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Gerald M. Heymsfield, Lin Tian, Andrew J. Heymsfield, Lihua Li, and Stephen Guimond

in various convective cells. There is a ∼6.5-dB increase in the reflectivity between the ice and water phase because of the increase in the dielectric coefficient ( Smith 1984 ). This results in sharp decreases in reflectivity above the 5–6-km altitude in many of the cases. We will discuss this subject further in section 4 . Three cases were especially strong compared to the others. Sea-breeze cases M and N (15 August 1998) had centimeter-size hail based on ground-based S-band polarimetric radar

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Robert Rogers

environmental, vortex, and convective scales. Kaplan and DeMaria (2003) , using the Statistical Hurricane Intensity Prediction Scheme (SHIPS) database, identified several environmental conditions associated with RI: warm sea surface temperatures and deep oceanic mixed layers, high lower-tropospheric relative humidity, low vertical shear, weak upper-level forcing from troughs or cold lows, and upper-level easterly flow. These findings are consistent with what has been found by previous observational and

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Stephen R. Guimond, Gerald M. Heymsfield, and F. Joseph Turk

-based indicators of inner core convection: 85-GHz ice-scattering signature and lightning. Mon. Wea. Rev. , 127 , 103 – 123 . Corbosiero , K. L. , and J. Molinari , 2002 : The effects of vertical wind shear on the distribution of convection in tropical cyclones. Mon. Wea. Rev. , 130 , 2110 – 2123 . DeMaria , M. , and J. Kaplan , 1994 : Sea surface temperature and the maximum intensity of Atlantic tropical cyclones. J. Climate , 7 , 1324 – 1334 . Demuth , J. L. , M. DeMaria , J. A

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Scott A. Braun, Michael T. Montgomery, Kevin J. Mallen, and Paul D. Reasor

horizontal and vertical scale of the vortex. They proposed that genesis would begin when the vertical scale had increased sufficiently to reach the surface. Hendricks et al. (2004) and Montgomery et al. (2006) have proposed an entirely different “bottom-up” deep-convection route to cyclogenesis that blends moist thermodynamic and dynamic processes and operates between the development of a weak cyclonic circulation near the sea surface and the ignition of the WISHE mechanism. In their high

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R. A. Hansell, S. C. Tsay, Q. Ji, N. C. Hsu, M. J. Jeong, S. H. Wang, J. S. Reid, K. N. Liou, and S. C. Ou

. Methodology a. Dust detection/retrieval Although we do not have direct measurements of sea salt concentrations, derived humidification factors f (85%) ( Jeong et al. 2007 , 2008 ), strongly suggest the presence of hygroscopic particles. Previous studies at Cape Verde reported that, on average, sea salt together with sulfates and carbonaceous aerosols contributed to a background AOT ( λ = 0.670 μ m) of only ∼0.04 ( Chiapello et al. 1999 ). As a note, the subtropical mean AOT (midvisible wavelengths

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Chanh Q. Kieu and Da-Lin Zhang

global models in predicting TC tracks indicate that the large-scale circulation is the key parameter in determining where TCG may occur. It is well known that the large-scale conditions conducive for TCG over different ocean basins include weak vertical wind shear ( Gray 1968 ; McBride and Zehr 1981 ; DeMaria 1996 ), warm sea surface temperature (SST) and deep moist layers ( Emanuel 2000 ), well-organized angular momentum fluxes ( Challa and Pfeffer 1990 ), easterly waves ( Molinari et al. 2000

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Zhuo Wang, M. T. Montgomery, and T. J. Dunkerton

parameter), vertical shear strong enough to tilt buoyant plumes off-center, or a burst of large-scale downdraft caused by evaporative cooling in the interior. 5. Predictability of tropical cyclogenesis Figure 6a shows the time series of the minimum sea level pressure (SLP) for the nine simulations, all derived from the 9-km resolution grid outputs. The simulations have quite different intensity evolution, with the minimum SLP at 2300 UTC 31 August (72 h in experiment HR) ranges from 1002 to 972 hPa

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Joël Arnault and Frank Roux

-moment mixed scheme and six classes of liquid and ice hydrometeors ( Pinty and Jabouille 1998 ). Turbulence is parameterized with the 1D scheme with a 1.5-order closure proposed by Bougeault and Lacarrère (1989) . Subgrid condensation is represented with the scheme proposed by Chaboureau and Bechtold (2005) , and radiative processes with the radiation scheme used at ECMWF ( Gregory et al. 2000 ). The model outputs are saved every hour. The diagnosed data contain the dynamic and thermodynamic variables as

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Zhaoxia Pu, Xuanli Li, and Juanzhen Sun

wind components and 5 dB Z for the observed radar reflectivity based on statistics of the large sample of the data. 4. Impacts of radar data assimilation on hurricane simulations To examine the impact of radar data assimilation on numerical simulation of Hurricane Dennis, numerical results from different experiments are compared during the time period between 0600 UTC 8 July and 0000 UTC 9 July 2005. a. The initial storm structure Figure 4 shows the sea level pressure (SLP) and surface wind

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