Ground-Based Velocity Track Display (GBVTD) Analysis of W-Band Doppler Radar Data in a Tornado near Stockton, Kansas, on 15 May 1999

2007 ◽  
Vol 135 (3) ◽  
pp. 783-800 ◽  
Author(s):  
Robin L. Tanamachi ◽  
Howard B. Bluestein ◽  
Wen-Chau Lee ◽  
Michael Bell ◽  
Andrew Pazmany
Keyword(s):  
Life Cycle ◽  
Wind Speed ◽  
Wind Profile ◽  
Doppler Radar ◽  
Radar Data ◽  
Vortex Center ◽  
Doppler Radar Data ◽  
University Of Oklahoma ◽  
W Band ◽  
The University

Abstract On 15 May 1999, a storm intercept team from the University of Oklahoma collected high-resolution, W-band Doppler radar data in a tornado near Stockton, Kansas. Thirty-five sector scans were obtained over a period of approximately 10 min, capturing the tornado life cycle from just after tornadogenesis to the decay stage. A low-reflectivity “eye”—whose diameter fluctuated during the period of observation—was present in the reflectivity scans. A ground-based velocity track display (GBVTD) analysis of the W-band Doppler radar data of the Stockton tornado was conducted; results and interpretations are presented and discussed. It was found from the analysis that the axisymmetric component of the azimuthal wind profile of the tornado was suggestive of a Burgers–Rott vortex during the most intense phase of the life cycle of the tornado. The temporal evolution of the axisymmetric components of azimuthal and radial wind, as well as the wavenumber-1, -2, and -3 angular harmonics of the azimuthal wind, are also presented. A quasi-stationary wavenumber-2 feature of the azimuthal wind was analyzed from 25 of the 35 scans. It is shown, via simulated radar data collection in an idealized Burgers–Rott vortex, that this wavenumber-2 feature may be caused by the translational distortion of the vortex during the radar scans. From the GBVTD analysis, it can be seen that the maximum azimuthally averaged azimuthal wind speed increased while the radius of maximum wind (RMW) decreased slightly during the intensification phase of the Stockton tornado. In addition, the maximum azimuthally averaged azimuthal wind speed, the RMW, and the circulation about the vortex center all decreased simultaneously as the tornado decayed.

scholarly journals EnKF Assimilation of High-Resolution, Mobile Doppler Radar Data of the 4 May 2007 Greensburg, Kansas, Supercell into a Numerical Cloud Model

2013 ◽  
Vol 141 (2) ◽  
pp. 625-648 ◽  
Author(s):  
Robin L. Tanamachi ◽  
Louis J. Wicker ◽  
David C. Dowell ◽  
Howard B. Bluestein ◽  
Daniel T. Dawson ◽  
...  
Keyword(s):  
Wind Profile ◽  
Doppler Radar ◽  
Cloud Model ◽  
Weather Prediction ◽  
Surface Wind ◽  
Radar Data ◽  
Data Availability ◽  
Cold Pool ◽  
Near Surface ◽  
Doppler Radar Data

Abstract Mobile Doppler radar data, along with observations from a nearby Weather Surveillance Radar-1988 Doppler (WSR-88D), are assimilated with an ensemble Kalman filter (EnKF) technique into a nonhydrostatic, compressible numerical weather prediction model to analyze the evolution of the 4 May 2007 Greensburg, Kansas, tornadic supercell. The storm is simulated via assimilation of reflectivity and velocity data in an initially horizontally homogeneous environment whose parameters are believed to be a close approximation to those of the Greensburg supercell inflow sector. Experiments are conducted to test analysis sensitivity to mobile radar data availability and to the mean environmental near-surface wind profile, which was changing rapidly during the simulation period. In all experiments, a supercell with similar location and evolution to the observed storm is analyzed, but the simulated storm’s characteristics differ markedly. The assimilation of mobile Doppler radar data has a much greater impact on the resulting analyses, particularly at low altitudes (≤2 km), than modifications to the near-surface environmental wind profile. Differences in the analyzed updrafts, vortices, cold pool structure, rear-flank gust front structure, and observation-space diagnostics are documented. An analyzed vortex corresponding to the enhanced Fujita scale 5 (EF-5) Greensburg tornado is stronger and deeper in experiments in which mobile (higher resolution) Doppler radar data are included in the assimilation. This difference is linked to stronger analyzed horizontal convergence, which in turn is associated with increased stretching of vertical vorticity. Changing the near-surface wind profile appears to impact primarily the updraft strength, availability of streamwise vorticity for tilting into the vertical, and low-level vortex strength and longevity.

A Variational Method for Filling in Missing Data in Doppler Velocity Fields

2021 ◽  
Author(s):  
VINCENT T. WOOD ◽  
ROBERT P. DAVIES-JONES ◽  
ALAN SHAPIRO
Keyword(s):  
Missing Data ◽  
Doppler Radar ◽  
Signal To Noise Ratio ◽  
Original Data ◽  
Radar Data ◽  
Velocity Fields ◽  
Doppler Velocity ◽  
Doppler Radar Data ◽  
Ground Clutter ◽  
Tornado Warnings

AbstractSingle-Doppler radar data are often missing in important regions of a severe storm due to low return power, low signal-to-noise ratio, ground clutter associated with normal and anomalous propagation, and missing radials associated with partial or total beam blockage. Missing data impact the ability of WSR-88D algorithms to detect severe weather. To aid the algorithms, we develop a variational technique that fills in Doppler velocity data voids smoothly by minimizing Doppler velocity gradients while not modifying good data. This method provides estimates of the analysed variable in data voids without creating extrema.Actual single-Doppler radar data of four tornadoes are used to demonstrate the variational algorithm. In two cases, data are missing in the original data, and in the other two, data are voided artificially. The filled-in data match the voided data well in smoothly varying Doppler velocity fields. Near singularities such as tornadic vortex signatures, the match is poor as anticipated. The algorithm does not create any velocity peaks in the former data voids, thus preventing false triggering of tornado warnings. Doppler circulation is used herein as a far-field tornado detection and advance-warning parameter. In almost all cases, the measured circulation is quite insensitive to the data that have been voided and then filled. The tornado threat is still apparent.

scholarly journals Retrieval of three-dimensional wind fields from Doppler radar data using an efficient two-step approach

2010 ◽  
Vol 3 (5) ◽  
pp. 4459-4495 ◽  
Author(s):  
C. López Carrillo ◽  
D. J. Raymond
Keyword(s):  
Variational Approach ◽  
Continuity Equation ◽  
Doppler Radar ◽  
Three Dimensional ◽  
Relevant Information ◽  
Radar Data ◽  
Wind Fields ◽  
Wind Retrieval ◽  
Complex Sampling ◽  
Doppler Radar Data

Abstract. In this work, we describe an efficient approach for wind retrieval from dual Doppler radar data. The approach produces a gridded field that not only satisfies the observations, but also satisfies the anelastic mass continuity equation. The method is based on the so-called three-dimensional variational approach to the retrieval of wind fields from radar data. The novelty consists in separating the task into steps that reduce the amount of data processed by the global minimization algorithm, while keeping the most relevant information from the radar observations. The method is flexible enough to incorporate observations from several radars, accommodate complex sampling geometries, and readily include dropsonde or sounding observations in the analysis. We demonstrate the usefulness of our method by analyzing a real case with data collected during the TPARC/TCS-08 field campaign.

Mapping of Airborne Doppler Radar Data

1994 ◽  
Vol 11 (2) ◽  
pp. 572-578 ◽  
Author(s):  
Wen-Chau Lee ◽  
Peter Dodge ◽  
Frank D. Marks ◽  
Peter H. Hildebrand
Keyword(s):  
Doppler Radar ◽  
Radar Data ◽  
Doppler Radar Data ◽  
Airborne Doppler Radar

Retrieved Thermodynamic Structure of Hurricane Rita (2005) from Airborne Multi-Doppler Radar Data

2021 ◽  
Author(s):  
Annette M. Boehm ◽  
Michael M. Bell
Keyword(s):  
Wind Shear ◽  
Doppler Radar ◽  
Three Dimensional ◽  
Vertical Wind Shear ◽  
Vertical Motion ◽  
Radar Data ◽  
Vertical Wind ◽  
Vertical Acceleration ◽  
Hurricane Rita ◽  
Doppler Radar Data

AbstractThe newly developed SAMURAI-TR is used to estimate three-dimensional temperature and pressure perturbations in Hurricane Rita on 23 September 2005 from multi-Doppler radar data during the RAINEX field campaign. These are believed to be the first fully three-dimensional gridded thermodynamic observations from a TC. Rita was a major hurricane at this time and was affected by 13 m s−1 deep-layer vertical wind shear. Analysis of the contributions of the kinematic and retrieved thermodynamic fields to different azimuthal wavenumbers suggests the interpretation of eyewall convective forcing within a three-level framework of balanced, quasi-balanced, and unbalanced motions. The axisymmetric, wavenumber-0 structure was approximately in thermal-wind balance, resulting in a large pressure drop and temperature increase toward the center. The wavenumber-1 structure was determined by the interaction of the storm with environmental vertical wind shear resulting in a quasi-balance between shear and shear-induced kinematic and thermo-dynamic perturbations. The observed wavenumber-1 thermodynamic asymmetries corroborate results of previous studies on the response of a vortex tilted by shear, and add new evidence that the vertical motion is nearly hydrostatic on the wavenumber-1 scale. Higher-order wavenumbers were associated with unbalanced motions and convective cells within the eyewall. The unbalanced vertical acceleration was positively correlated with buoyant forcing from thermal perturbations and negatively correlated with perturbation pressure gradients relative to the balanced vortex.

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