Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Circulation around a Constrained Curve: An Alternative Analysis Tool for Diagnosing the Origins of Tornado Rotation in Numerical Supercell Simulations

Circulation around a Constrained Curve: An Alternative Analysis Tool for Diagnosing the Origins... AbstractFine-resolution computer models of supercell storms generate realistic tornadic vortices. Like real tornadoes, the origins of these virtual vortices are mysterious. To diagnose the origin of a tornado, typically a near-ground material circuit is drawn around it. This circuit is then traced back in time using backward trajectories. The rate of change of the circulation around the circuit is equal to the total force circulation. This circulation theorem is used to deduce the origins of the tornado’s large vorticity. However, there is a well-known problem with this approach; with staggered grids, parcel trajectories become uncertain as they dip into the layer next to the ground where horizontal wind cannot be interpolated. To circumvent this dilemma, we obtain a generalized circulation theorem that pertains to any circuit. We apply this theorem either to moving circuits that are constrained to simple surfaces or to a “hybrid” circuit defined next. Let A be the horizontal surface at one grid spacing off the ground. Above A the circuit moves as a material circuit. Horizontal curve segments that move in A with the horizontal wind replace segments of the material circuit that dip below A. The circulation equation for the modified circuit includes the force circulation of the inertial force that is required to keep the curve segments horizontal. This term is easily evaluated on A. Use of planar or circular circuits facilitates explanation of some simple flows. The hybrid-circuit method significantly improves the accuracy of the circulation budget in an idealized supercell simulation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of the Atmospheric Sciences American Meteorological Society

Circulation around a Constrained Curve: An Alternative Analysis Tool for Diagnosing the Origins of Tornado Rotation in Numerical Supercell Simulations

Download PDF
15 pages

Loading next page...
 
/lp/american-meteorological-society/circulation-around-a-constrained-curve-an-alternative-analysis-tool-pCzoZw3vwU
Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0469
eISSN
1520-0469
DOI
10.1175/JAS-D-21-0020.1
Publisher site
See Article on Publisher Site

Abstract

AbstractFine-resolution computer models of supercell storms generate realistic tornadic vortices. Like real tornadoes, the origins of these virtual vortices are mysterious. To diagnose the origin of a tornado, typically a near-ground material circuit is drawn around it. This circuit is then traced back in time using backward trajectories. The rate of change of the circulation around the circuit is equal to the total force circulation. This circulation theorem is used to deduce the origins of the tornado’s large vorticity. However, there is a well-known problem with this approach; with staggered grids, parcel trajectories become uncertain as they dip into the layer next to the ground where horizontal wind cannot be interpolated. To circumvent this dilemma, we obtain a generalized circulation theorem that pertains to any circuit. We apply this theorem either to moving circuits that are constrained to simple surfaces or to a “hybrid” circuit defined next. Let A be the horizontal surface at one grid spacing off the ground. Above A the circuit moves as a material circuit. Horizontal curve segments that move in A with the horizontal wind replace segments of the material circuit that dip below A. The circulation equation for the modified circuit includes the force circulation of the inertial force that is required to keep the curve segments horizontal. This term is easily evaluated on A. Use of planar or circular circuits facilitates explanation of some simple flows. The hybrid-circuit method significantly improves the accuracy of the circulation budget in an idealized supercell simulation.

Journal

Journal of the Atmospheric Sciences – American Meteorological Society

Published: Oct 1, 2021

References

  • A numerical simulation of cyclic mesocyclogenesis
    Adlerman, E. J.; Droegemeier, K. K.; Davies-Jones, R. P.
  • Tornadogenesis and early Tornado evolution in the El Reno, Oklahoma, supercell on 31 May 2013
    Bluestein, H. B.; Thiem, K. J.; Snyder, J. C.; Houser, J. B.
  • Near-ground rotation in simulated supercells: On the robustness of the baroclinic mechanism
    Dahl, J. M. L.
  • Uncertainties in trajectory calculations within near-surface mesocyclones of simulated supercells
    Dahl, J. M. L.; Parker, M. D.; Wicker, L. J.
  • Imported and storm-generated near-ground vertical vorticity in a simulated supercell
    Dahl, J. M. L.; Parker, M. D.; Wicker, L. J.
  • Streamwise vorticity: The origin of updraft rotation in supercell storms
    Davies-Jones, R.
  • Growth of circulation around supercell updrafts
    Davies-Jones, R.
  • Can a descending rain curtain in a supercell instigate tornadogenesis barotropically?
    Davies-Jones, R.
  • A review of supercell and tornado dynamics
    Davies-Jones, R.
  • Simulated Doppler velocity signatures of evolving tornado-like vortices
    Davies-Jones, R.; Wood, V. T.
  • Tornadoes and tornadic storms
    Davies-Jones, R.; Trapp, R. J.; Bluestein, H. B.
  • Chaotic streamlines in the ABC flows
    Dombre, T.; Frisch, U.; Greene, J. M.; Henon, M.; Mahr, A.; Soward, A. M.
  • A theory for the maximum windspeed in tornado-like vortices
    Fiedler, B. H.; Rotunno, R.
  • Wind speed and air flow patterns in the Dallas tornado of April 2, 1957
    Hoecker, W. H.
  • An idealized numerical simulation investigation of the effects of surface drag on the development of near-surface vertical vorticity in supercell thunderstorms
    Markowski, P. M.
  • The influence of environmental low-level shear and cold pools on tornadogenesis: Insights from idealized simulations
    Markowski, P. M.; Richardson, Y. P.
  • Tornadogenesis resulting from the transport of circulation by a downdraft: Idealized numerical simulations
    Markowski, P. M.; Straka, J. M.; Rasmussen, E. N.
  • The pretornadic phase of the Goshen County, Wyoming, supercell of 5 June 2009 intercepted by VORTEX2. Part II: Intensification of low-level rotation
    Markowski, P. M.
  • Observations of near-surface vertical wind profiles and vertical momentum fluxes from VORTEX-SE 2017: Comparisons to Monin–Obukhov similarity theory
    Markowski, P. M.; Lis, N. T.; Turner, D. D.; Lee, T. R.; Buban, M. S.
  • Geophysical vortices
    Morton, B. R.
  • Evolution of a long-track violent tornado within a simulated supercell
    Orf, L.; Wilhelmson, R.; Lee, B.; Finley, C.; Houston, A.
  • The role of surface drag in mesocyclone intensification leading to tornadogenesis within an idealized supercell simulation
    Roberts, B.; Xue, M.
  • The role of surface drag in tornadogenesis within an idealized supercell simulation
    Roberts, B.; Xue, M.; Schenkman, A. D.; Dawson, D. T.
  • The effect of surface drag strength on mesocyclone intensification and tornadogenesis in idealized supercell simulations
    Roberts, B.; Xue, M.; Dawson, D. T.
  • On the viscous core of a line vortex
    Rott, N.
  • On the rotation and propagation of simulated supercell thunderstorms
    Rotunno, R.; Klemp, J. B.
  • Numerical study of the 6 May 2012 Tsukuba supercell tornado: Vorticity sources responsible for tornadogenesis
    Tao, T.; Tamura, T.
  • Tornado-like vortexgenesis in a simplified numerical model
    Trapp, R. J.; Fiedler, B. H.
  • Low-level mesovortices within squall lines and bow echoes. Part II: Their genesis and implications
    Trapp, R. J.; Weisman, M. L.
  • Important factors for tornadogenesis as revealed by high-resolution ensemble forecasts of the Tsukuba supercell tornado of 6 May 2012 in Japan
    Yokota, S.; Niino, H.; Seko, H.; Kunii, M.; Yamauchi, H.