Tornado vortex signature
A tornadic vortex signature, abbreviated TVS, is a Pulse-Doppler radar weather radar detected rotation algorithm that indicates the likely presence of a strong mesocyclone that is in some stage of tornadogenesis.[1] It may give meteorologists the ability to pinpoint and track the location of tornadic rotation within a larger storm, and is one component of the National Weather Service's warning operations.[2]
The tornadic vortex signature was first identified by Donald W. Burgess, Leslie R. Lemon, and Rodger A. Brown in the 1970s using experimental Doppler radar at the National Severe Storms Laboratory (NSSL) in Norman, Oklahoma. The National Weather Service (NWS) now uses an updated algorithm developed by NSSL, the tornado detection algorithm (TDA) based on data from its WSR-88D system of radars. NSSL also developed the mesocyclone detection algorithm (MDA).[3]
Display
The conditions causing a TVS are often visible on the
Intensity
A TVS can be measured by intense gate to gate wind shear, which is the change of wind speed and/or direction across the two gates of inbound and outbound velocities. Gates are the individual pixels on the radar display. For example, if the inbound velocity is −48 knots (−89 km/h) and the outbound is 39 knots (72 km/h), then there is 87 knots (161 km/h) of gate to gate shear.[7] The impressiveness of a TVS not only has to do with the strength of the gate to gate shear, but it also incorporates the size and depth of the TVS, and the strength of any surrounding mesocyclone, among other factors, including several vertically-polarized variables with the advent of dual-polarization.[8]
See also
- Convective storm detection
- Hook echo
- Bounded weak echo region (BWER)
- Cooperative Institute for Mesoscale Meteorological Studies, Center for Analysis and Prediction of Storms, Advanced Radar Research Center
Notes
- ^ WSR-88D Distance Learning Operations Course, slides 3 & 4
- ^ "NWS Radar: Key Indicators in Warning Decisions". National Weather Service.
- ^ "Tornado Detection". Severe Weather 101. National Severe Storms Laboratory. Retrieved 2014-05-17.
- ^ WSR-88D Distance Learning Operations Course, slides 3 & 4
- ^ WSR-88D Distance Learning Operations Course, slide 13
- ^ WSR-88D Distance Learning Operations Course, slide 30
- ^ WSR-88D Distance Learning Operations Course, slide 4
- ^ WSR-88D Distance Learning Operations Course, slide 9
References
- Paul Schlatter, Warning Decision Training Branch (September 2009). "WSR-88D Distance Learning Operations Course; Topic 5, Lesson 21". Online. Retrieved 2009-11-29.
- Rodger Brown and Vincent Wood, National Severe Storms Laboratory (April 2012). "The Tornadic Vortex Signature: An Update". Weather and Forecasting. 27 (2). Online: 525–530. S2CID 122590037. Retrieved 2020-03-26.