Examples of spectral fields Tornadic Spectra - May 8, 2003 Svetlana Bachmann 04/13/2005

The fields of spectral moments from data collected with the KOUN radar during a tornadic event (May 8, 2003) The fields of spectral moments re estimated using both time and frequency domain methods. equivalent reflectivity factor (dBZ) mean Doppler velocity spectrum width In Time Domain In Frequency Domain

Region with the tornado Spectra for azimuths from 24 to 34. Y-axis shows range gate number (1 km = 4 range gates), X-axis shows spectral coefficient number (zero velocity is in the center), color-scale shows power in logarithmic units. Tornado spectra are evident in radials 28.5, 29, 29.5, 30 at ~100th ranges gate (~ 25 km) Z v w In non-tornadic regions spectra exhibit maxima at the wind velocity. At the regions with ground clutter spectra show two maxima at wind and at zero-velocities. The width of the maxima are narrow. At the tornado region spectra are multimodal and wide.

Azimuth 5 10 15 20 25 30 35 -35 35 Velocity Range, km Tornado