A Variational Method for Analyzing Vortex Flows in Radar-Scanned Tornadic Mesocyclones. Part IV: Applications to the 20 May 2013 Oklahoma Tornadic Mesocyclone

Details

• Journal Title:
  Journal of the Atmospheric Sciences
• Personal Author:
  Xu, Qin ; Wei, Li ; Nai, Kang
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; NSSL (National Severe Storms Laboratory) ; CIWRO (Cooperative Institute for Severe and High-Impact Weather Research and Operations)
• Description:
  The variational method for vortex flow (VF) analyses, called VF-Var (formulated in Part I), is applied to the 20 May 2013 Newcastle–Moore tornadic mesocyclone observed from the operational KTLX radar and an experimental phased-array radar. The dual-Doppler-analyzed VF field reveals the following features: The axisymmetric part of the VF is a well-defined slantwise two-cell vortex in which the maximum tangential velocity is nearly 40 m s−1 at the edge of the vortex core (0.6 km from the vortex center), the central downdraft velocity reaches −35 m s−1 at 3-km height, and the surrounding-updraft velocity reaches 26 m s−1 at 5-km height. The total VF field is a loosely defined slantwise two-cell vortex consisting of a nearly axisymmetric vortex core (in which the ground-relative surface wind speed reaches 50 m s−1 on the southeast edge), a strong nonaxisymmetric slantwise downdraft in the vortex core, and a main updraft in a banana-shaped area southeast of the vortex core, which extends slantwise upward and spirals cyclonically around the vortex core. The single-Doppler analysis with observations from the KTLX radar only exhibits roughly the same features as the dual-Doppler analysis but contains spurious vertical-motion structures in and around the vortex core. Analysis errors are assessed by leveraging the findings from Parts II and III, which indicate that the dual-Doppler-analyzed VF is accurate enough to represent the true VF but the single-Doppler-analyzed VF is not (especially for nonaxisymmetric vertical motions in and around the vortex core), so the dual-Doppler-analyzed VF should be useful for initializing/verifying high-resolution tornado simulations.
• Keywords:
  Radar Tornadoes Mesocyclones Radar Observations Variational Analysis Vortices
• Source:
  Journal of the Atmospheric Sciences, 79(6), 1531-1547
• DOI:
  https://doi.org/10.1175/JAS-D-21-0247.1
• Document Type:
  Journal Article
• Funding:
  Grant no. NA16OAR4320072
• Rights Information:
  Other
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:910b808748179bfc4867d34fc6e4a35a9980c3a38a307d4c689826f53377136c
• Download URL:
  https://repository.library.noaa.gov/view/noaa/43760/noaa_43760_DS1.pdf
• File Type:
  [PDF - 3.71 MB ]