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Chanh Q. Kieu and Da-Lin Zhang

multinested (36/12/4/1.33) km grids captures well main characteristics of the storm during its life cycle from the early genesis to the dissipation stages without bogusing any data into the model initial conditions. Both the observations and model simulation show the merger of two mesovortices (hereafter V 1 and V 2 ) associated with the ITCZ breakdowns during the formation of TS Eugene (see Fig. 1a ). Here the merging period begins as V 2 ’s southerly flow decreases in intensity and coverage with the

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

I . The control run has a four-grid nested domain configuration with horizontal grid spacing 81, 27, 9, and 3 km, respectively, initialized at 0000 UTC 29 August 2007, about 3 days prior to genesis. The initial conditions and lateral boundary forcing in the control run were derived from the ECMWF 6-hourly analyses with T106 resolution. The Kain–Fritsch scheme was used to represent cumulus convection in the two outer grids; in the two inner grids (9-km and 3-km resolution), cumulus convection was

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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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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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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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Wallace Hogsett and Da-Lin Zhang

dilution of TPE due to density changes. For the purposes of this study, we will consider TPE to be simply the intermediary between LE and KE, both of which will be the focus of the present study. The KE equation can be obtained by taking the dot product of the MM5 horizontal momentum equation: where KE changes because of horizontal cross-isobaric flow when work is done by air parcels against the horizontal pressure force (KGEN), friction including the boundary layer processes and vertical and

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Edward K. Vizy and Kerry H. Cook

top of the atmosphere set at 50 hPa, and a 30-km grid spacing with a model time step of 1 min. The domain is large ( Fig. 1 ) to encompass much of northern and tropical Africa and the Atlantic Ocean. The model is run in synoptic mode with initial and lateral boundary conditions for temperature, horizontal wind, geopotential height, relative humidity, land surface temperature, and soil moisture taken from the 6-hourly 1.125° ECMWF operational reanalysis. SSTs are prescribed and updated every 6 h as

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

Radiative Transfer Model (RRTM) longwave ( Mlawer et al. 1997 ) and Dudhia shortwave ( Dudhia 1989 ) schemes. Initial and boundary conditions are obtained from 6-hourly National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) analyses with 1° resolution using the WRF preprocessing system software. Experiments were run with multiple initialization times to determine which times provided the best reproduction of the evolution of Gert as verified by aircraft and satellite

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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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Wei Zhong, Da-Lin Zhang, and Han-Cheng Lu

variables with the subscript “0”, will be treated as constants around r = r 0 . After eliminating υ ′ and h ′ (see the appendix ), we obtain a second-order ordinary differential equation in the unknown variable ũ : where ω = ω̂ − Ω 0 n ≠ 0 and c 0 = gH is the phase velocity of surface gravity waves and is considered to be constant. Equation (7) is a homogeneous equation, so we may expect that nontrivial solutions satisfying appropriate boundary conditions will exist for certain values

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