Doppler Radar Wind Spectra of Supercell Tornadoes

Bluestein, Howard B.; LaDue, James G.; Stein, Herbert; Speheger, Douglas A.; Unruh, Wesley F.

doi:10.1175/1520-0493(1993)121<2200:drwsos>2.0.co;2

Cited by 68 publications

(25 citation statements)

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“…However, no declaration will be made here about the extent or frequency of such amplification in natural tomadoes. Bluestein et al (1993) present portable Doppler radar measurements of maximum wind speeds in six tomadoes along with the convective available potential energy (CAPE) in the environment of the storms. In their Table 3, the lower bound on dimensionless Vmax for the six tomadoes is 1.26, 0.98, 0.72, 1.38, 0.92 and 1.22 when non-dimensionalized with 2CAPE.…”

Section: Discussionmentioning

confidence: 99%

The thermodynamic speed limit and its violation in axisymmetric numerical simulations of tornado‐like vortices

Fiedler

1994

Atmosphere-Ocean

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Section: Discussionmentioning

confidence: 99%

The thermodynamic speed limit and its violation in axisymmetric numerical simulations of tornado‐like vortices

Fiedler

1994

Atmosphere-Ocean

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“…Subsequent studies examining radial velocities based on Doppler radars measurements were able to resolve the mesocyclone and the tornadic-vortex signature (TVS), which can be associated with the parent circulation of the tornado and the tornado, respectively (e.g., Brown et al 1978). More recently, successful intercepts of supercell storms with mobile Doppler radars have provided unprecedented, close-up views of the structure of the hook echo and the intense circulation within and surrounding the tornado (e.g., Bluestein et al 1993Bluestein et al , 1997Bluestein et al , 2004Bluestein et al , 2007aWurman et al 1996a;Wurman and Gill 2000;Alexander and Wurman 2005;Wurman et al 2007a,b). One of the characteristic features within the hook echo is the weak-echo hole (WEH), first documented by Fujita (1981).…”

Section: Introductionmentioning

confidence: 99%

“…While these past studies have collected a plethora of data on the echo structure and velocity fields in tornadoes, careful analysis of pictures taken at the same time have been relatively rare (Bluestein et al 1993(Bluestein et al , 1997(Bluestein et al , 2004(Bluestein et al , 2007aWakimoto et al 2003). Photogrammetric analysis is important since it provides quantitative information about the tornado (e.g., condensation funnel width).…”

Section: Introductionmentioning

confidence: 99%

The LaGrange Tornado during VORTEX2. Part I: Photogrammetric Analysis of the Tornado Combined with Single-Doppler Radar Data

Wakimoto

Atkins

Wurman

2011

Monthly Weather Review

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This study presents a single-Doppler radar analysis combined with cloud photography of the LaGrange, Wyoming, tornado on 5 June 2009 in an attempt to relate the radar-observed hook echo, weak-echo hole (WEH), and rotational couplet to the visual characteristics of the tornado. The tornado was rated EF2. The circulation at low levels went through two intensification periods based on azimuthal shear measurements. The first intensification was followed by the appearance of a brief funnel cloud. The second intensification was coincident with the appearance of a second funnel cloud that remained in contact with the ground until the tornado dissipated.A deep WEH rapidly formed within the hook echo after damaging wind was identified at the ground and before the appearance of a funnel cloud. The echo pattern through the hook echo on 5 June undergoes a dramatic evolution. Initially, the minimum radar reflectivities are near the surface (,15 dBZ) and the WEH does not suggest a tapered structure near the ground. Subsequently, higher reflectivities appear at low levels when the funnel cloud makes contact with the ground. During one analysis time, the increase of the echo within the WEH at low levels results in a couplet of high/low radar reflectivity in the vertical. This increase in echo at low levels is believed to be associated with lofted debris although none was visibly apparent until the last analysis time. The WEH was nominally wider than the visible funnel cloud. The dataset provides the first detailed analysis of the double-ring structure within a hook echo that has been reported in several studies. The inner high-reflectivity region is believed to be a result of lofted debris. At higher-elevation angles, a small secondary WEH formed within the first WEH when debris was lofted and centrifuged.A feature noted in past studies showing high-resolution vertical cross sections of single-Doppler velocity normal to the radar beam is an intense rotational couplet of negative and positive values in the lowest few hundred meters. This couplet was also evident in the analysis of the LaGrange tornado. The couplet was asymmetric with stronger negative velocities owing to the motion of the tornado toward the radar. The damaging wind observed by radar extended well beyond the condensation funnel in the lowest few hundred meters. However, another couplet indicating strong rotation was also noted aloft in a number of volume scans. The decrease in rotational velocities between the low-and upper-level couplets may be related to air being forced radially outward from the tornado center at a location above the intense inflow.

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“…Though we certainly all could agree to exclude random molecular motion as a valid contestant in the windspeed sweepstakes, there could be some disagreement on how to judge random turbulent events. We may wish to allow those that could conceivably be detected by Doppler radar techniques, as in Bluestein et al (1993). We may wish to disallow small random events that inevitably must occur, but are not detectable by present technology.…”

Section: Introductionmentioning

confidence: 99%

“…Instead, we present a fair intellectual challenge. Observations (Bluestein et al, 1993) have shown that the thermodynamic speed limit is being broken in tornadoes; the pressure deficit is apparently not limited by that which is hydrostatic. (The thermodynamic speed limit is the windspeed implied by the convective available potential energy, or CAPE, in a sounding, and is so named because meteorologists obtain it from a thermodynamic diagram.)…”

Section: Introductionmentioning

confidence: 99%

Compressibility and windspeed limits in tornadoes

Fiedler¹

1997

Atmosphere-Ocean

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Doppler Radar Wind Spectra of Supercell Tornadoes

Cited by 68 publications

References 0 publications

The thermodynamic speed limit and its violation in axisymmetric numerical simulations of tornado‐like vortices

The thermodynamic speed limit and its violation in axisymmetric numerical simulations of tornado‐like vortices

The LaGrange Tornado during VORTEX2. Part I: Photogrammetric Analysis of the Tornado Combined with Single-Doppler Radar Data

Compressibility and windspeed limits in tornadoes

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