Tornado debris signature

[1][2] A TDS may also be indicated by dual-polarization radar products, designated as a polarimetric tornado debris signature (PTDS).

Polarimetric radar can discern meteorological and nonmeteorological hydrometeors and the co-location of a PTDS with the enhanced reflectivity of a debris ball are used by meteorologists as confirmation that a tornado is occurring.

As a result of the strong winds required to damage structures and loft debris into the air, debris balls are normally the result of EF3 or stronger tornadoes on the Enhanced Fujita Scale.

[1] A debris ball on radar images can verify tornadoes 70–80% of the time.

[6] An algorithm, called Polarimetric Tornado Debris Signature (PTDS), was developed by researchers by combining polarimetric data with reflectivity and velocity data, showing areas with a probability of detection greater than 80%.

Image showing two radar images. On the left is a base reflectivity radar image, which displays precipitation. On the right is a storm relative velocity radar image, which shows direction and intensity of wind speeds.
On the left, a typical debris ball shown as an area of high reflectivity on the end of the hook echo of the parent supercell of the 2011 Joplin tornado co-located with a velocity couplet on the right
Comparison of four radar products: reflectivity, Z, top left; velocity, SRM, top right; and polarimetric products, differential reflectivity, Z DR , on bottom left; correlation coefficient, CC, on bottom right, used to identify TDSs