Editorial Type:
Article
Article Type:
Research Article

The VDAC Technique: A Variational Method for Detecting and Characterizing Convective Vortices in Multiple-Doppler Radar Data

Corey K. Potvin School of Meteorology, and Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma

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Alan Shapiro School of Meteorology, and Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma

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Michael I. Biggerstaff School of Meteorology, University of Oklahoma, Norman, Oklahoma

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Joshua M. Wurman Center for Severe Weather Research, Boulder, Colorado

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Print Publication:
01 Aug 2011
DOI:
https://doi.org/10.1175/2011MWR3638.1
Page(s):
2593–2613
Restricted access

Abstract

The vortex detection and characterization (VDAC) technique is designed to identify tornadoes, mesocyclones, and other convective vortices in multiple-Doppler radar data and retrieve their size, strength, and translational velocity. The technique consists of fitting radial wind data from two or more radars to a simple analytical model of a vortex and its near environment. The model combines a uniform flow, linear shear flow, linear divergence flow (all of which comprise a broad-scale flow), and modified combined Rankine vortex. The vortex and its environmental flow are allowed to translate. A cost function accounting for the discrepancy between the model and observed radial winds is evaluated over space and time so that observations can be used at the actual times and locations they were acquired. The model parameters are determined by minimizing this cost function.

Tests of the technique using analytically generated, numerically simulated, and one observed tornadic wind field were presented by Potvin et al. in an earlier study. In the present study, an improved version of the technique is applied to additional real radar observations of tornadoes and other substorm-scale vortices. The technique exhibits skill in detecting such vortices and characterizing their size and strength. Single-Doppler experiments suggest that the technique may reliably detect and characterize larger (>1-km diameter) vortices even in the absence of overlapping radar coverage.

Corresponding author address: Corey K. Potvin, National Severe Storms Laboratory, Forecast Research and Development Division, Room 4355, 120 David L. Boren Blvd., Norman, OK 73072. E-mail: corey.potvin@noaa.gov

Abstract

The vortex detection and characterization (VDAC) technique is designed to identify tornadoes, mesocyclones, and other convective vortices in multiple-Doppler radar data and retrieve their size, strength, and translational velocity. The technique consists of fitting radial wind data from two or more radars to a simple analytical model of a vortex and its near environment. The model combines a uniform flow, linear shear flow, linear divergence flow (all of which comprise a broad-scale flow), and modified combined Rankine vortex. The vortex and its environmental flow are allowed to translate. A cost function accounting for the discrepancy between the model and observed radial winds is evaluated over space and time so that observations can be used at the actual times and locations they were acquired. The model parameters are determined by minimizing this cost function.

Tests of the technique using analytically generated, numerically simulated, and one observed tornadic wind field were presented by Potvin et al. in an earlier study. In the present study, an improved version of the technique is applied to additional real radar observations of tornadoes and other substorm-scale vortices. The technique exhibits skill in detecting such vortices and characterizing their size and strength. Single-Doppler experiments suggest that the technique may reliably detect and characterize larger (>1-km diameter) vortices even in the absence of overlapping radar coverage.

Corresponding author address: Corey K. Potvin, National Severe Storms Laboratory, Forecast Research and Development Division, Room 4355, 120 David L. Boren Blvd., Norman, OK 73072. E-mail: corey.potvin@noaa.gov
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  • Biggerstaff, M. I., and Coauthors, 2005: The Shared Mobile Atmospheric Research and Teaching Radar: A collaboration to enhance research and teaching. Bull. Amer. Meteor. Soc., 86, 1263–1274.

    • Search Google Scholar
    • Export Citation

  • Bluestein, H. B., W.-C. Lee, M. Bell, C. C. Weiss, and A. L. Pazmany, 2003: Mobile Doppler radar observations of a tornado in a supercell near Bassett, Nebraska, on 5 June 1999. Part II: Tornado-vortex structure. Mon. Wea. Rev., 131, 2968–2984.

    • Search Google Scholar
    • Export Citation

  • Bluestein, H. B., M. M. French, R. L. Tanamachi, S. Frasier, K. Hardwick, F. Junyent, and A. L. Pazmany, 2007: Close-range observations of tornadoes in supercells made with a dual-polarization, X-band, mobile Doppler radar. Mon. Wea. Rev., 135, 1522–1543.

    • Search Google Scholar
    • Export Citation

  • Brotzge, J., and S. Erickson, 2010: Tornadoes without NWS warning. Wea. Forecasting, 25, 159–172.

  • Brotzge, J., and Coauthors, 2007: CASA IP1: Network operations and initial data. Extended Abstracts, 23rd Conf. on Interactive Information and Processing Systems, San Antonio, TX, Amer. Meteor. Soc., 8A.6. [Available online at http://ams.confex.com/ams/87ANNUAL/techprogram/paper_120056.htm.]

    • Search Google Scholar
    • Export Citation

  • Brotzge, J., K. Hondl, B. Philips, L. Lemon, E. J. Bass, D. Rude, and D. L. Andra, 2010: Evaluation of distributed collaborative adaptive sensing for detection of low-level circulations and implications for severe weather warning operations. Wea. Forecasting, 25, 173–189.

    • Search Google Scholar
    • Export Citation

  • Brown, R. A., V. T. Wood, and D. Sirmans, 2002: Improved tornado detection using simulated and actual WSR-88D data with enhanced resolution. J. Atmos. Oceanic Technol., 19, 1759–1771.

    • Search Google Scholar
    • Export Citation

  • Center for Severe Weather Research, cited 2010: Preliminary radar analysis of the Geary-Calumet, Oklahoma tornadoes occurring on 29 May 2004. [Available online at http://www.cswr.org/dataimages/rotate/geary-summary-2004-0711fp.pdf.]

    • Search Google Scholar
    • Export Citation

  • Crum, T. D., and R. L. Alberty, 1993: The WSR-88D and the WSR-88D Operational Support Facility. Bull. Amer. Meteor. Soc., 74, 1669–1687.

    • Search Google Scholar
    • Export Citation

  • Fletcher, R., and C. M. Reeves, 1964: Function minimization by conjugate gradients. Comput. J., 7, 149–153.

  • Fujita, T. T., 1981: Tornadoes and downbursts in the context of generalized planetary scales. J. Atmos. Sci., 38, 1511–1534.

  • Gal-Chen, T., 1982: Errors in fixed and moving frames of reference: applications for conventional and Doppler radar analysis. J. Atmos. Sci., 39, 2279–2300.

    • Search Google Scholar
    • Export Citation

  • Hughes, L. A., 1952: On the low-level wind structure of tropical storms. J. Meteor., 9, 422–428.

  • Junyent, F., V. Chandrasekar, D. McLaughlin, E. Insanic, and N. Bharadwaj, 2010: The CASA Integrated Project 1 networked radar system. J. Atmos. Oceanic Technol., 27, 61–78.

    • Search Google Scholar
    • Export Citation

  • Kuhlman, K. M., D. R. MacGorman, M. I. Biggerstaff, and P. R. Krehbiel, 2009: Lightning initiation in the anvils of two supercell storms. Geophys. Res. Lett., 36, L07802, doi:10.1029/2008GL036650.

    • Search Google Scholar
    • Export Citation

  • Lee, W.-C., and J. Wurman, 2005: Diagnosed three-dimensional axisymmetric structure of the Mulhall tornado on 3 May 1999. J. Atmos. Sci., 62, 2373–2393.

    • Search Google Scholar
    • Export Citation

  • Lee, W.-C., F. D. Marks Jr., and R. E. Carbone, 1994: Velocity track display—A technique to extract real-time tropical cyclone circulations using a single airborne Doppler radar. J. Atmos. Oceanic Technol., 11, 337–356.

    • Search Google Scholar
    • Export Citation

  • Lee, W.-C., B. J.-D. Jou, P.-L. Chang, and S.-M. Deng, 1999: Tropical cyclone kinematic structure retrieved from single-Doppler radar observations. Part I: Interpretation of Doppler velocity patterns and the GBVTD technique. Mon. Wea. Rev., 127, 2419–2439.

    • Search Google Scholar
    • Export Citation

  • Lewellen, D. C., W. S. Lewellen, and J. Xia, 2000: The influence of a local swirl ratio on tornado intensification near the surface. J. Atmos. Sci., 57, 527–544.

    • Search Google Scholar
    • Export Citation

  • Liou, Y.-C., T.-C. Chen Wang, W.-C. Lee, and Y.-J. Chang, 2006: The retrieval of asymmetric tropical cyclone structures using Doppler radar simulations and observations with the extended GBVTD technique. Mon. Wea. Rev., 134, 1140–1160.

    • Search Google Scholar
    • Export Citation

  • MacGorman, D. R., and Coauthors, 2008: TELEX: The Thunderstorm Electrification and Lightning Experiment. Bull. Amer. Meteor. Soc., 89, 997–1013.

    • Search Google Scholar
    • Export Citation

  • Marquis, J., Y. Richardson, P. Markowski, D. Dowell, and J. Wurman, 2011: Tornado maintenance investigated with high-resolution dual-Doppler and EnKF analysis. Mon. Wea. Rev., in press.

    • Search Google Scholar
    • Export Citation

  • McGrath, K. M., T. A. Jones, and J. T. Snow, 2002: Increasing the usefulness of a mesocyclone climatology. Preprints, 21st Conf. on Severe Local Storms, San Antonio, TX, Amer. Meteor. Soc., 162–165.

    • Search Google Scholar
    • Export Citation

  • McLaughlin, D., and Coauthors, 2005: Distributed Collaborative Adaptive Sensing (DCAS) for improved detection, understanding, and predicting of atmospheric hazards. Extended Abstracts, Ninth Symp. on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface, San Diego, CA, Amer. Meteor. Soc., 11.3. [Available online at http://ams.confex.com/ams/Annual2005/techprogram/paper_87890.htm.]

    • Search Google Scholar
    • Export Citation

  • Mitchell, E. D., S. V. Vasiloff, G. J. Stumpf, A. Witt, M. D. Eilts, J. T. Johnson, and K. W. Thomas, 1998: The National Severe Storms Laboratory tornado detection algorithm. Wea. Forecasting, 13, 352–366.

    • Search Google Scholar
    • Export Citation

  • Payne, C. D., T. J. Schuur, D. R. MacGorman, M. I. Biggerstaff, K. Kuhlman, and W. D. Rust, 2010: Polarimetric and electrical characteristics of a lightning ring in a supercell storm. Mon. Wea. Rev., 138, 2405–2425.

    • Search Google Scholar
    • Export Citation

  • Polak, E., and G. Ribiere, 1969: Note sur la convergence de methods de directions conjuguees. Rev. Franc. Informat. Rech. Operationnelle, 16, 35–43.

    • Search Google Scholar
    • Export Citation

  • Potvin, C. K., A. Shapiro, T. Y. Yu, J. Gao, and M. Xue, 2009: Using a low-order model to detect and characterize tornadoes in multiple-Doppler radar data. Mon. Wea. Rev., 137, 1230–1249.

    • Search Google Scholar
    • Export Citation

  • Roux, F., and F. D. Marks, 1996: Extended velocity track display (EVTD): An improved processing method for Doppler radar observation of tropical cyclones. J. Atmos. Oceanic Technol., 13, 875–899.

    • Search Google Scholar
    • Export Citation

  • Stumpf, J. G., A. Witt, E. D. Mitchell, P. L. Spencer, J. T. Johnson, M. D. Eilts, K. W. Thomas, and D. W. Burgess, 1998: The National Severe Storms Laboratory mesocyclone detection algorithm for the WSR-88D. Wea. Forecasting, 13, 304–326.

    • Search Google Scholar
    • Export Citation

  • Wurman, J., 2002: The multiple-vortex structure of a tornado. Wea. Forecasting, 17, 473–505.

  • Wurman, J., and S. Gill, 2000: Finescale radar observations of the Dimmitt, Texas (2 June 1995), tornado. Mon. Wea. Rev., 128, 2135–2164.

    • Search Google Scholar
    • Export Citation

  • Wurman, J., J. Straka, E. Rasmussen, M. Randall, and A. Zahrai, 1997: Design and deployment of a portable, pencil-beam, pulsed, 3-cm Doppler radar. J. Atmos. Oceanic Technol., 14, 1502–1512.

    • Search Google Scholar
    • Export Citation
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