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

2100 UTC 31 August 2007 by the NHC. The WRF model was initialized at 0000 UTC 29 August 2007, about 3 days prior to genesis. Initial conditions and lateral boundary forcing for the control run were derived from the ECMWF 6-hourly analyses with T106 resolution (about 1.125° × 1.125°). Simulation on the innermost grid began six hours later (at 0600 UTC 29 August 2007) to allow for some model adjustment. In the control simulation, the Kain–Fritsch scheme ( Kain and Fritsch 1990 ) was used to represent

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Chanh Q. Kieu and Da-Lin Zhang

1. Introduction Despite considerable progress in the forecasts of tropical cyclone (TC) track and intensity during the past few decades, tropical cyclone genesis (TCG), a process by which a weak atmospheric disturbance grows into a tropical storm (TS), still remains elusive, partly because of the lack of high-resolution observations at the very early stage of TCG and partly because of the deficiencies in current TC models. In general, there are numerous tropical disturbances of different scales

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Chuntao Liu, Earle R. Williams, Edward J. Zipser, and Gary Burns

existence of abundant rainfall in shallow convection can be explained by weak updrafts in the vicinity of cloud base height or by the sparsity of cloud condensation nuclei in the marine boundary layer ( Williams and Stanfill 2002 ). For improved understanding of the global electrical circuit, it is important to quantify the precipitation current in convective storms with different intensity and attendant vertical development. Further observations of electrical charges on precipitation above the

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Jonathan L. Vigh and Wayne H. Schubert

the coefficients A , B , and C . However, for applications to tropical cyclones, there are several disadvantages to Eliassen’s approach: (i) the effects of top and bottom boundary conditions and the circular geometry are not included, (ii) the important spatial variability of the inertial stability coefficient C is not included, and (iii) the diabatic heating is localized in z , whereas in tropical cyclones it is rather smoothly distributed over the whole troposphere [for examples of

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John Molinari and David Vollaro

circumstances are much less likely over water. The current note will not consider shallow supercells typical of hurricane landfall environments, which are well understood as a result of the work of McCaul and Weisman (1996 , 2001) and various other papers since. The cells of interest in this note are deep cells in tropical cyclones over open ocean. They are supported by local vertical shear maxima that arise not from the landfall process but rather from the response of the tropical cyclone to large

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Oreste Reale, William K. Lau, Kyu-Myong Kim, and Eugenia Brin

important to emphasize that the processes of cyclogenesis and cyclogenesis suppression should be studied from different perspectives, and global models do have two unquestionable advantages: 1) they are better at capturing the large-scale forcings involved, and 2) do not rely upon the somewhat questionable boundary conditions imposed on the domain’s boundaries of limited-area models. Among the large-scale problems connected with Atlantic tropical cyclogenesis, one of the most debated is the role of the

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Joël Arnault and Frank Roux

Fritsch 1993 ; Bechtold et al. 2001 ). The simulated domain is 4800 km × 4800 km horizontally ( Fig. 1 ). The vertical grid has 66 levels from the surface to 28 km with a grid spacing of 60 m near the surface up to 600 m at the tropopause level, and the orography is taken into account with the Gal-Chen and Sommerville (1975) vertical coordinate. This simulation is coupled with ECMWF operational analyses every 6 h at the boundaries of the simulated domain. Microphysics is parameterized with a one

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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

profiles of pressure, temperature, and water vapor density to be input for calculating the diurnal variability of the dust DRE LW . Considering the size of Sal Island (∼216 km 2 ) and assuming that it is effectively an ocean site, we use a constant surface albedo/emissivity of 0.02/0.99, respectively, to constrain the model surface boundary conditions. We also input an averaged retrieved ocean surface skin temperature of 26°C for the study period using the NOAA Advanced Very High Resolution Radiometer

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Syed Ismail, Richard A. Ferrare, Edward V. Browell, Gao Chen, Bruce Anderson, Susan A. Kooi, Anthony Notari, Carolyn F. Butler, Sharon Burton, Marta Fenn, Jason P. Dunion, Gerry Heymsfield, T. N. Krishnamurti, and Mrinal K. Biswas

during NAMMA showed the occurrence of rapid enhancements and subsequent decreases in aerosol content of the SAL every few days. Episodic SAL events with distinctive boundaries and sudden intensity enhancements as seen in satellite imagery (and confirmed by lidar backscatter observations) are termed “SAL events” in this paper. The SAL is a synoptic-scale feature containing warm, dust-laden air transported from the Sahel and Saharan regions of northern Africa ( Carlson and Prospero 1972 ). The layers

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

the peak value of the mean profile was ∼13–14 m s −1 . The updrafts we analyze in this paper are larger than this; thus, we define hot towers as a special class of deep convection [the largest peak updrafts in the Black et al. (1996) and Heymsfield et al. (2010) populations]. There is evidence that downdrafts play an important role in HTs and VHTs as well. Heymsfield et al. (2001) analyzed EDOP data from Hurricane Bonnie (1998) and found a deep, broad subsidence current on the inner edge of

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