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David R. Novak, Brian A. Colle, and Ron McTaggart-Cowan

forcing for ascent due to diabatic processes within the trough of warm air aloft, or trowal (e.g., Godson 1951 ; Martin 1998a , b ), was at least twice as large as horizontal deformation. Furthermore, there is an emerging view that diabatically generated PV anomalies ( Raymond 1992 ) are common features of extratropical cyclones (e.g., Davis 1992 ; Stoelinga 1996 ; Wernli et al. 2002 ; Moore and Montgomery 2004 ), and that they may affect mesoscale precipitation distribution (e.g., Brennan and

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Manda B. Chasteen, Steven E. Koch, and David B. Parsons

developed near the terminus of the LLJ and triggered both gravity waves and bores, which initiated subsequent convection. During the morning, this elevated convection evolved into a surface-based MCS. Trier et al. (2011) examined this case using a WRF-ARW simulation and found that mesoscale processes were important for conditioning the inflow environment of the MCS and that the system lacked a well-defined cold pool until midmorning, which suggests that it had been maintained via elevated convergence

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Michael M. Bell and Michael T. Montgomery

maximum value of 0.78 at the 850-hPa level. Negative correlation with below 700 hPa with similar magnitudes suggest a prominent role of the diurnal and convective cycle in the meso- α -scale RH time series. Positive correlations ranging between 0.2 and 0.6 of the stretching tendency with time series below 700 hPa (not shown) suggest that moisture recovery was also important to the convective processes. 5. Discussion and conclusions Observations of the mesoscale processes leading to tropical

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Russ S. Schumacher and Richard H. Johnson

that explicitly predict but do not truly resolve convective processes. It will also be shown that the mesoscale structure of the simulated system when using 3-km grid spacing (i.e., without domain 3) is generally similar to that at 1-km grid spacing. Because of this similarity, a few sensitivity experiments will be presented that use this setup, which is significantly less computationally expensive. Also, given the larger size of the 3-km grid, some synoptic and larger mesoscale features will be

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X. Capet, J. C. McWilliams, M. J. Molemaker, and A. F. Shchepetkin

analyzed in terms of its primary dynamical processes. Surface density fronts form in the regions of high strain on the flanks of mesoscale eddies. Frontogenesis sharpens them down to a horizontal scale of a few kilometers or less in association with an ageostrophic secondary circulation mostly confined to the surface boundary layer. This submesoscale process efficiently releases potential energy and acts effectively to restratify the upper ocean, even though only a small fraction of the domain is

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Hironori Fudeyasu, Yuqing Wang, Masaki Satoh, Tomoe Nasuno, Hiroaki Miura, and Wataru Yanase

strong environmental stretching deformation field, whereas the reintensification was associated with the eyewall reformation as a result of the axisymmetrization of an inward-propagating outer spiral rainband. In this paper, we will document the system-scale and mesoscale processes in the life cycle of the simulated Isobel with the focus on processes related to the genesis and intensity change of the simulated Isobel. The genesis remains the least understood stage in the life cycle of a tropical

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Benjamin J. Moore, Paul J. Neiman, F. Martin Ralph, and Faye E. Barthold

, this paper examines the AR event of 1–2 May 2010 with specific focus on diagnosing 1) the synoptic-scale processes and flow features facilitating water vapor transport from the tropics into the central Mississippi Valley, and 2) the role of the AR in producing nearly continuous heavy convective rainfall over a 2-day period. Within the latter component, the mesoscale conditions and physical mechanisms that served to focus heavy rainfall along a relatively narrow corridor in Tennessee and Kentucky

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Wolfgang Hanft and Adam L. Houston

their small size places them at the limits of resolution of conventional observation networks and most current numerical weather prediction models. Moreover, since the processes responsible for their formation are not fully understood, conceptual models and forecasting heuristics have not been developed. This study aims to examine MAHTE characteristics using data collected within a MAHTE and to examine the possible mechanisms for MAHTE formation through mesoscale modeling. Deep convection forming on

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Sergio F. Abarca and Michael T. Montgomery

-dimensional mesoscale model in which we study an integration that undergoes a canonical eyewall replacement cycle. For this simulation, it is shown that secondary eyewall formation occurs in a region of the vortex where azimuthal averages of equivalent potential temperature and absolute angular momentum surfaces are far from being congruent. This result questions the applicability of moist-neutral viewpoints and related mathematical formulations thereto for studying this process of tropical cyclone intensity change

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Stanley B. Trier, Christopher A. Davis, David A. Ahijevych, and Kevin W. Manning

representing the mesoscale environmental thermodynamic variations often associated with CI. In the current paper we develop a method, based on parcel theory, that allows us to evaluate the influence of different physical processes on the evolution of the mesoscale thermodynamic vertical structure. Case studies with a convection-permitting numerical model are used to demonstrate the method and examine how these physical processes modify thermodynamic environments allowing the initiation of observed

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