skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Mobile Radar Observations of the Evolving Debris Field Compared with a Damage Survey of the Shawnee, Oklahoma, Tornado of 19 May 2013
Title: Mobile Radar Observations of the Evolving Debris Field Compared with a Damage Survey of the Shawnee, Oklahoma, Tornado of 19 May 2013
A detailed damage survey is combined with high-resolution mobile, rapid-scanning X-band polarimetric radar data collected on the Shawnee, Oklahoma, tornado of 19 May 2013. The focus of this study is the radar data collected during a period when the tornado was producing damage rated EF3. Vertical profiles of mobile radar data, centered on the tornado, revealed that the radar reflectivity was approximately uniform with height and increased in magnitude as more debris was lofted. There was a large decrease in both the cross-correlation coefficient ( ρ hv ) and differential radar reflectivity ( Z DR ) immediately after the tornado exited the damaged area rated EF3. Low ρ hv and Z DR occurred near the surface where debris loading was the greatest. The 10th percentile of ρ hv decreased markedly after large amounts of debris were lofted after the tornado leveled a number of structures. Subsequently, ρ hv quickly recovered to higher values. This recovery suggests that the largest debris had been centrifuged or fallen out whereas light debris remained or continued to be lofted. Range–height profiles of the dual-Doppler analyses that were azimuthally averaged around the tornado revealed a zone of maximum radial convergence at a smaller radius relative to the leading edge of lofted debris. Low-level inflow into the tornado encountering a positive bias in the tornado-relative radial velocities could explain the existence of the zone. The vertical structure of the convergence zone was shown for the first time.  more » « less
Award ID(s):
1823478 1947146
PAR ID:
10149719
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
Monthly Weather Review
Volume:
148
Issue:
5
ISSN:
0027-0644
Page Range / eLocation ID:
1779 to 1803
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, Monthly Weather Review)
    Abstract An EF1 tornado was documented using photographs, a high-resolution video, and a mobile radar as it entered Selden, KS on 24 May 2021. The kinematic structure of the tornadic wind field was presented by tracking lofted debris and analyzing single-Doppler velocities. Tracking of debris on the side of the tornado farthest from the observer was possible due to the transparent nature of the debris cloud. The analysis suggests that the circulation was axisymmetric with the maximum horizontal velocities located at low levels. The positive vertical velocities were strongest on the forward side of the tornado. The maximum vertical velocities were associated with a secondary vortex. For the first time, the data set provided an opportunity to assess the orientation of a large, lofted debris based on the images recorded by a movie and compare these observations with the differential radar reflectivity (ZDR) recorded by a mobile polarimetric radar. T-matrix calculations of wood boards yielded a mean ZDRthat was negative and was also observed in the ZDRanalysis suggesting a preference for lofted debris to be vertically oriented. 
    more » « less
  2. ; ; (, Monthly weather review)
    This study utilizes data collected by the University of Oklahoma Advanced Radar Research Center’s Polarimetric Radar for Innovations in Meteorology and Engineering (OU-PRIME) C-band radar as well as the federal KTLX and KOUN WSR-88D S-band radars to study a supercell that simultaneously produced a long-track EF-4 tornado and an EF-2 landspout tornado (EF indicates the enhanced Fujita scale) near Norman, Oklahoma, on 10 May 2010. Contrasting polarimetric characteristics of two tornadoes over similar land cover but with different intensities are documented. Also, the storm-scale sedimentation of debris within the supercell is investigated, which includes observations of rotation and elongation of a tornadic debris signature with height. A dual-wavelength comparison of debris at S and C bands is performed. These analyses indicate that lofted debris within the tornado was larger than debris located outside the damage path of the tornado and that debris size outside the tornado increased with height, likely as the result of centrifuging. Profiles of polarimetric variables were observed to become more vertically homogeneous with time. 
    more » « less
  3. ; ; ; (, Journal of Applied Meteorology and Climatology)
    null (Ed.)
    Abstract Fully polarimetric scanning and vertically pointing Doppler spectral data from the state-of-the-art Stony Brook University Ka-band Scanning Polarimetric Radar (KASPR) are analyzed for a long-duration case of ice pellets over central Long Island in New York from 12 February 2019. Throughout the period of ice pellets, a classic refreezing signature was present, consisting of a secondary enhancement of differential reflectivity Z DR beneath the melting layer within a region of decreasing reflectivity factor at horizontal polarization Z H and reduced copolar correlation coefficient ρ hv . The KASPR radar data allow for evaluation of previously proposed hypotheses to explain the refreezing signature. It is found that, upon entering a layer of locally generated columnar ice crystals and undergoing contact nucleation, smaller raindrops preferentially refreeze into ice pellets prior to the complete freezing of larger drops. Refreezing particles exhibit deformations in shape during freezing, leading to reduced ρ hv , reduced co-to-cross-polar correlation coefficient ρ xh , and enhanced linear depolarization ratio, but these shape changes do not explain the Z DR signature. The presence of columnar ice crystals, though apparently crucial for instigating the refreezing process, does not contribute enough backscattered power to affect the Z DR signature, either. 
    more » « less
  4. ; ; (, Journal of Applied Meteorology and Climatology)
    Quasi-vertical profiles (QVPs) obtained from a database of U.S. WSR-88D data are used to document polarimetric characteristics of the melting layer (ML) in cold-season storms with high vertical resolution and accuracy. A polarimetric technique to define the top and bottom of the ML is first introduced. Using the QVPs, statistical relationships are developed to gain insight into the evolution of microphysical processes above, within, and below the ML, leading to a statistical polarimetric model of the ML that reveals characteristics that reflectivity data alone are not able to provide, particularly in regions of weak reflectivity factor at horizontal polarization ZH. QVP ML statistics are examined for two regimes in the ML data: ZH≥ 20 dB Z and ZH< 20 dB Z. Regions of ZH≥ 20 dB Z indicate locations of MLs collocated with enhanced differential reflectivity ZDRand reduced copolar correlation coefficient ρhv, while for ZH< 20 dB Z a well-defined ML is difficult to discern using ZHalone. Evidence of large ZDRup to 4 dB, backscatter differential phase δ up to 8°, and low ρhvdown to 0.80 associated with lower ZH(from −10 to 20 dB Z) in the ML is observed when pristine, nonaggregated ice falls through it. Positive correlation is documented between maximum specific differential phase KDPand maximum ZHin the ML; these are the first QVP observations of KDPin MLs documented at S band. Negative correlation occurs between minimum ρhvin the ML and ML depth and between minimum ρhvin the ML and the corresponding enhancement of ZH(Δ ZH= ZHmax− ZHrain). 
    more » « less
  5. ; (, Weather and Forecasting)
    Abstract Downbursts pose a threat to life, property, and aviation, yet they remain challenging to predict. Prior studies have found radar-based downburst signatures such as divergent and convergent velocity signatures at the surface and midlevels, respectively; descending radar reflectivity (Z) cores (DRCs); present or descending specific differential phase (KDP) cores; and troughs of decreased differential reflectivity (ZDR) collocated with decreased copolar correlation coefficient (ρhv) below the melting layer. This research expands on those studies using the multicell identification and tracking (MCIT) algorithm to automate storm detection and analyze 53 downburst cases spanning most regions of the CONUS. Individual case analysis revealed that DRCs appeared in 83% of cases, descendingKDPcores appeared in 85% of cases, andZDRtroughs and collocatedρhvdrops appeared in 89% of cases. The magnitude of low-level divergence and midlevel convergence reached a threshold of 0.0025 s−1in 68% and 83% of cases, respectively. Composite time series revealed that divergence displayed the most prominent signature near the surface; aloft,KDPat and 1 km below the freezing level, midlevel convergence,ZDRcolumn area and volume, and VIL displayed the most prominent signatures. Differences were observed between geographic regions and thermodynamic environments, with lower velocity-related and higherKDP-related values most common in the eastern United States and environments with wind index (WINDEX) < 60; conversely, higher velocity-related and lowerKDP-related values were most common in the western United States and environments with WINDEX > 60. These findings may help inform future polarimetric downburst detection and algorithm development efforts. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email