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

pouch extending to the boundary layer helps to keep (within the pouch) whatever moisture is lofted by deep convection into the free atmosphere, thereby creating a favorable environment for sustained convection, midlevel moistening, and further development. It is possible to view the vertical interaction between lower-tropospheric easterly waves and near-surface ITCZ features in a complementary way, noting that the ITCZ is a region of frequent deep convection, low-level cyclonic vorticity and

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

at middle to upper levels around 1200 UTC 23 July. Convection resumed around 1800 UTC 23 July ( Fig. 2d ) and then increased substantially by 0600 UTC 24 July (cf. Fig. 2f ). After 1200 UTC 24 July, decreasing low-level upward motion and increasing upward motion aloft indicated a growing influence of stratiform precipitation processes. To better delineate the roles of convective and stratiform processes during the simulation, Fig. 10 shows the area-weighted averages of vertical motion for

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Edward K. Vizy and Kerry H. Cook

the first AEW’s passage were unfavorable for development. The passage of the first wave over the Cape Verde region is associated with strong low to-middle tropospheric vertical shear owing to a stronger than normal AEJ, lower than normal relative humidity values throughout the troposphere between 10° and 20°N, and an overall more stable atmosphere between 15° and 25°W. All of these environmental conditions are characteristics generally associated with an intensification of the SAL, or a SAL

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Zhaoxia Pu, Xuanli Li, and Juanzhen Sun

Jindo, South Korea, were assimilated for the prediction of the landfalling Typhoon Rusa (2002). A noticeable improvement in the short-range prediction of the precipitation was produced by the radar data assimilation. Zhao and Jin (2008) assimilated observations from five Weather Surveillance Radar-1988 Doppler (WSR-88D) radars for Hurricane Isabel (2003). With the Navy’s Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS), they assimilated radar reflectivity and radial velocity data

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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

that deficiencies in the modeling of moisture and diabatic processes are due in part to the lack of knowledge of the tropical humidity fields. Model forecasts are very sensitive to the surface layer moisture. Krishnamurti and Oosterhof (1989) showed that models that incorporated an explicitly resolved surface layer were able to more accurately compute the strong moisture flux between the ocean and atmosphere, resulting in more accurate prediction of the formation of hurricanes. Results from the

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Joël Arnault and Frank Roux

differences, we consider that a quantitative analysis of the energetic growth of this simulated developing system can provide valuable information on the processes occurring in the real atmosphere. The Hovmöller diagram of the ECMWF analyzed relative vorticity at 700 hPa ( Fig. 2c ) shows the zonally moving AEW trough, associated with the previously described convective activity. We therefore suggest the synoptic AEW could have interacted with convection. The Hovmöller diagram of the model

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Wallace Hogsett and Da-Lin Zhang

KE, w 2 /2, is excluded because it is one to two orders of magnitude smaller than the horizontal component. We start from a prognostic equation for LE, which is essentially the available water vapor contained in the atmosphere, to account for the most crucial component for TC development and maintenance. It is obtained by multiplying the water vapor budget equation from Zhang et al. (2002) by the latent heat of vaporization, L υ : where the three rhs terms represent sources and sinks of LE

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

and azimuthal WN ( n ). Thus, it is natural to examine to what extent the wave solutions so derived make sense when they are applied to realistic TCs. For this purpose, Fig. 7 shows the distribution of Q as a function of radius for the two long waves (i.e., n = 2, 3), with all the basic-state variables specified from the model atmosphere as given in Figs. 1 and 2 . An eigenvalue of m = 1.5 is used in plotting Fig. 7 because around this value the sign of Q changes with different

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Robert Cifelli, Timothy Lang, Steven A. Rutledge, Nick Guy, Edward J. Zipser, Jon Zawislak, and Robert Holzworth

trough, within the trough passage, and to the rear of the trough. Sounding data (up to four times daily during the life cycle of wave 5) was collected at all three sites corresponding to the radar locations [Praia—Tropical Ocean and Global Atmosphere (TOGA) radar; Dakar—(NPOL) radar; and Niamey—Massachusetts Institute of Technology (MIT) radar]. These data were quality controlled by the principal AMMA–NAMMA investigators for each sounding system. Examination of upper-air sounding data at each

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Robert Rogers

altitude) in the 6–12-h time period prior to RI onset. The relationship between vertical velocity, divergence, and PV evolution prior to RI supports the work of Hertenstein and Schubert (1991) and Tory et al. (2006) , who found that the stratiform region primarily enhances PV in the middle levels, while the convective region enhances PV in the lower troposphere. b. Convective bursts The time–height series in Fig. 11 show intermittent periods of strong mean 2–10-km inner-core upward motion. These

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