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Daniel P. Betten, Michael I. Biggerstaff, and Louis J. Wicker

1. Introduction One of the most commonly used methods to characterize three-dimensional motion in complex flows is to examine Lagrangian trajectories. In supercell storms, conclusions about the behavior and source of low-level vortices in numerical simulations ( Rotunno and Klemp 1985 ; Wicker and Wilhelmson 1995 ; Adlerman et al. 1999 ; Mashiko et al. 2009 ; Schenkman et al. 2014 ) and observational studies ( Johnson et al. 1987 ; Wakimoto et al. 1998 ; Ziegler et al. 2001 ; Markowski

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Jessica M. Erlingis, Jonathan J. Gourley, and Jeffrey B. Basara

regions as well as the predominant flow paths at several levels in the lower atmosphere. Section 4 provides a synthesis of the first part of the manuscript and introduces the content of the companion paper. 2. Methodology This study uses the wind fields in North American Regional Reanalysis (NARR; NCEP 2005 ; Mesinger et al. 2006 ) data to calculate kinematic backward trajectories for a database of flash flood events in order to assess the geographic origins of parcels that contribute to flash

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L. Baker Perry, Charles E. Konrad, and Thomas W. Schmidlin

and moisture limited to below 700 hPa, with topography and convection providing the necessary forcing. In many cases, trajectories extend downwind from the Great Lakes into the study area ( Fig. 1 ). The general synoptic environment, therefore, displays certain characteristics that are associated with lake-effect snowfall (LES) in the Great Lakes region, for example, a shallow moist layer that is present beneath a capping inversion (e.g., Niziol et al. 1995 ; Lackmann 2001 ). One important

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Julian F. Quinting and Michael J. Reeder

temperature increase in producing heat waves? The study ends with the conclusions in section 5 . 2. Dataset and methodology All analyses presented in this paper are based on 6-hourly ERA-Interim ( Dee et al. 2011 ) on a regular 0.75° latitude–longitude grid. Climatological means in this study always refer to averages over the 30-yr period 1981–2010. a. Definition of southeastern Australian heat waves The characteristics of trajectories during southeastern Australian heat waves for the period DJF 1989

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Volfango Rupolo

, even inside relatively small subdomains, different regimes of dispersion may exist, because of the huge variability of Lagrangian behaviors (e.g., the coexistence of looping and nonlooping trajectories; Veneziani et al. 2004 ). Consequently, the computation of statistical parameters by means of simple and unconditioned means among Lagrangian trajectories experiencing different flow regimes may give rise to misleading results. The complicated nature of Lagrangian dispersion has been evidenced also

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Matthias Lankhorst

1. Introduction The imprint of eddy vorticity in particle trajectories can be by shear and curvature. With field experiments in mind, data density is typically low and thus insufficient to deduce synoptic shear vorticity. The search for eddies in such trajectories is then restricted to analyzing curvature. With the aim of finding coherent vortices and deducing their internal structure, one would want to identify several revolutions around an eddy center, in contrast to shorter arclike “curves

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Christopher M. Fuhrmann and Charles E. Konrad II

cyclogenesis, upstream convection, cold-air damming, and lower-tropospheric potential vorticity maxima ( Lackmann 2006 ). In the present study, we build upon these methods and models by using a trajectory approach to identify the upstream atmospheric features and physical processes that contribute both to precipitation type and intensity across central North Carolina. A trajectory can be defined as simply the path that an air parcel takes over space and time. With improvements in model resolution and

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Thomas A. Cram, John Persing, Michael T. Montgomery, and Scott A. Braun

(2002) and compute several thousand three-dimensional Lagrangian trajectories for air parcels seeded throughout the eye, eyewall, and surrounding regions of Hurricane Bonnie. The large number of Lagrangian trajectories is used to gather a census of the behavior and thermodynamic properties of air parcels in various regions of the simulated hurricane. Although Bonnie represents only a single case, and results gleaned from it cannot easily be generalized, we believe the methodology developed herein

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Andrew Vande Guchte and Johannes M. L. Dahl

1. Introduction Recent literature in the study of simulated severe convection has made frequent use of parcel trajectory analysis (e.g., Rotunno and Klemp 1985 ; Wicker and Wilhelmson 1995 ; Adlerman et al. 1999 ; Dahl et al. 2012 ; Naylor et al. 2012 ; Beck and Weiss 2013 ; Markowski and Richardson 2014 ; Dahl et al. 2014 ; Markowski et al. 2014 ; Schenkman et al. 2014 ; Coffer and Parker 2015 ; Dahl 2015 ; Davenport and Parker 2015 ; Dawson et al. 2016 ; Rotunno et al. 2017

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Johannes M. L. Dahl, Matthew D. Parker, and Louis J. Wicker

1. Introduction The origin of vertical vorticity in tornadoes is one of the most critical questions about tornadogenesis. A widely used approach to address this problem, both in models and dual-Doppler analyses, is the backward integration of trajectories initialized within the near-surface vortex. Based on these trajectories, vorticity or circulation budgets following individual parcels may be computed. However, these budgets—and the inferred sources of vorticity—critically depend on the

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