Editorial Type:
Article
Article Type:
Research Article

The Impact of Range-Oversampling Processing on Tornado Velocity Signatures Obtained from WSR-88D Superresolution Data

Sebastián M. Torres Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and NOAA/OAR/National Severe Storms Laboratory, Norman, Oklahoma

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Christopher D. Curtis Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and NOAA/OAR/National Severe Storms Laboratory, Norman, Oklahoma

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Print Publication:
01 Sep 2015
DOI:
https://doi.org/10.1175/JTECH-D-14-00196.1
Page(s):
1581–1592
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Abstract

WSR-88D superresolution data are produced with finer range and azimuth sampling and improved azimuthal resolution as a result of a narrower effective antenna beamwidth. These characteristics afford improved detectability of weaker and more distant tornadoes by providing an enhancement of the tornadic vortex signature, which is characterized by a large low-level azimuthal Doppler velocity difference. The effective-beamwidth reduction in superresolution data is achieved by applying a tapered data window to the samples in the dwell time; thus, it comes at the expense of increased variances for all radar-variable estimates. One way to overcome this detrimental effect is through the use of range oversampling processing, which has the potential to reduce the variance of superresolution data to match that of legacy-resolution data without increasing the acquisition time. However, range-oversampling processing typically broadens the radar range weighting function and thus degrades the range resolution. In this work, simulated Doppler velocities for vortexlike fields are used to quantify the effects of range-oversampling processing on the velocity signature of tornadoes when using WSR-88D superresolution data. The analysis shows that the benefits of range-oversampling processing in terms of improved data quality should outweigh the relatively small degradation to the range resolution and thus contribute to the tornado warning decision process by improving forecaster confidence in the radar data.

Corresponding author address: Sebastián Torres, National Weather Center, 120 David L. Boren Blvd., Norman, OK 73072. E-mail: sebastian.torres@noaa.gov

Abstract

WSR-88D superresolution data are produced with finer range and azimuth sampling and improved azimuthal resolution as a result of a narrower effective antenna beamwidth. These characteristics afford improved detectability of weaker and more distant tornadoes by providing an enhancement of the tornadic vortex signature, which is characterized by a large low-level azimuthal Doppler velocity difference. The effective-beamwidth reduction in superresolution data is achieved by applying a tapered data window to the samples in the dwell time; thus, it comes at the expense of increased variances for all radar-variable estimates. One way to overcome this detrimental effect is through the use of range oversampling processing, which has the potential to reduce the variance of superresolution data to match that of legacy-resolution data without increasing the acquisition time. However, range-oversampling processing typically broadens the radar range weighting function and thus degrades the range resolution. In this work, simulated Doppler velocities for vortexlike fields are used to quantify the effects of range-oversampling processing on the velocity signature of tornadoes when using WSR-88D superresolution data. The analysis shows that the benefits of range-oversampling processing in terms of improved data quality should outweigh the relatively small degradation to the range resolution and thus contribute to the tornado warning decision process by improving forecaster confidence in the radar data.

Corresponding author address: Sebastián Torres, National Weather Center, 120 David L. Boren Blvd., Norman, OK 73072. E-mail: sebastian.torres@noaa.gov
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Journal of Atmospheric and Oceanic Technology

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