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Yi Dai, Sharanya J. Majumdar, and David S. Nolan

. Frank and Ritchie (2001) argued that the upper-level warm core was ventilated by the environmental flow, leading to top-down weakening by hydrostatic adjustment of low-level pressure. In addition to the midlevel ventilation, the environment shear can also result in a low-level ventilation by downward flushing of low-entropy air from the middle levels to the boundary layer (e.g., Tang and Emanuel 2010 ; Riemer et al. 2010 ). However, TCs can sometimes intensify under moderately strong shear (5

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David R. Ryglicki, Daniel Hodyss, and Gregory Rainwater

visualization and interpretation. An a posteriori analysis indicates that the three largest terms on the right-hand side ultimately become the divergent flux of divergent kinetic energy, the pressure gradient term, and the conversion term, but, as we shall show, there are important details in this evolution reflecting the transition shown in Fig. 4c at 48 h. Fig . 13. Spatial structure at 13 km of (top) rotational kinetic energy, (middle) divergent kinetic energy, and (bottom) cross-term energy for (a

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Robert G. Nystrom and Fuqing Zhang

discussed. Fig . 1. (top) Real-time operational guidance, HWRF (dashed) and NHC official forecasts (solid), (middle) deterministic WRF forecasts from assimilation of conventional observations only, and (bottom) deterministic WRF forecasts from assimilation of conventional observations plus P-3 Doppler radial velocity super observations. Both sets of deterministic WRF forecasts utilize 1 km horizontal grid spacing for the innermost domain. The WRF forecasts initialized immediately following P-3 flights

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Benjamin C. Trabing, Michael M. Bell, and Bonnie R. Brown

complexities of the real atmosphere make diagnosing the impact of individual PI parameters very difficult. In this study, we employ a high-resolution, three-dimensional, full-physics model on a “weather” time scale of 8 days to diagnose the physical mechanisms behind why changing upper-tropospheric temperatures modify TC intensification, and to investigate the use of PI theory in understanding TC maximum intensity on weather time scales. One potential mechanism by which a colder upper

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Russell L. Elsberry, Eric A. Hendricks, Christopher S. Velden, Michael M. Bell, Melinda Peng, Eleanor Casas, and Qingyun Zhao

water vapor bands are most sensitive to the middle- to upper-tropospheric humidity. Given this high spatial, spectral, and temporal resolution, these new-generation imagers are better able to track coherent clouds and water vapor features to derive atmospheric motion vectors (AMVs) that provide estimates of tropospheric winds ( Velden et al. 2005 ). That is, clouds or water vapor features can be selected from an image at time t and then the backward and forward motion vectors from t − 10 min to

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Eric A. Hendricks, Russell L. Elsberry, Christopher S. Velden, Adam C. Jorgensen, Mary S. Jordan, and Robert L. Creasey

km to the south between 11.5 and 14.5 km ( Fig. 5b ). Although there are also some small oscillations about the vertical inferred from the ZWCs in the middle troposphere, the Joaquin vortex at 1800 UTC 3 October will be considered to be near-vertical between 1.5 and 14.5 km ( Table 2 ). By 1800 UTC 4 October, Joaquin had rapidly decayed to 85 kt in response to large VWS ( Fig. 2 ). A markedly different vortex structure ( Fig. 5c ) was diagnosed by Creasey and Elsberry (2017) based on the HDSS

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David R. Ryglicki, James D. Doyle, Yi Jin, Daniel Hodyss, and Joshua H. Cossuth

the behavior is quite different. Fig . 3. (top) Minimum pressure, (middle) MMTW, and (bottom) RMW, all at the lowest scalar model level, for the four simulations. Dark red lines correspond to the first RI period, the levelling off of intensification, and the second abrupt RI. The 7.5 m s −1 Gaussian-shear simulation goes through several stages on its path to RI. Deviation from the control begins 24 h into the simulation. This is followed by 3.5 days of steady intensification. A briefer (or a

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David R. Ryglicki, James D. Doyle, Daniel Hodyss, Joshua H. Cossuth, Yi Jin, Kevin C. Viner, and Jerome M. Schmidt

Part II ; however, this section will provide a brief review of the results particularly relevant for this study. Figure 1 (reproduced from Part II ) illustrates the minimum pressure, maximum mean tangential wind, and RMW of the four simulations from Part II . As noted in Part II , the control develops, the G7.5 TC develops, the C7.5 TC does not develop, and the G11.5 TC does not develop. Fig . 1. (top) Minimum pressure, (middle) maximum mean tangential wind, and (bottom) radius of maximum

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William A. Komaromi and James D. Doyle

1. Introduction Until recently, a single ER-2 flight over Hurricane Erin (2001) provided the only direct dropsonde observations through the full depth of the tropical cyclone (TC) outflow layer ( Halverson et al. 2006 ). Conventional aircraft observations of TCs, such as by the U.S. Air Force C-130s and the NOAA P-3s, tend to be limited to the middle to lower levels of the cyclone with a typical flight level of 700 hPa ( Aberson et al. 2006 ). Synoptic observations provided by the NOAA G-IV are

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William A. Komaromi and James D. Doyle

to systematically explore the effect of modifying the environmental inertial stability and the resulting effect on the strength, structure, and direction of the storm outflow. Last, predictability issues associated with TC intensity change and the relative positions of the TC and the trough will be investigated. 2. Methodology a. Numerical model configuration The numerical simulations in this study are performed using the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) for Tropical

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