Wind Speeds in Two Tornadic Storms and a Tornado, Deduced from Doppler Spectra

Dusan Zrnic National Severe Storms Laboratory, Norman, OK 73069

Search for other papers by Dusan Zrnic in
Current site
Google Scholar
PubMed
Close
and
Michael Istok National Severe Storms Laboratory, Norman, OK 73069

Search for other papers by Michael Istok in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

Doppler spectra of a tornado were collected with a radar having a large unambiguous velocity range, ±91 m s−1. Thus for the first time a presentation of nonaliased spectra was possible, showing direct measurement of radial velocities. By fitting the tornado model spectrum to data, the radius of maximum winds and tornado center location are deduced. Tornado spectral signature is defined as a double peak, symmetric with respect to the mean wind spectrum. Histograms of maximum measured wind speeds (from spectrum skirts) for two tornadic storms are obtained, and the histograms of velocity difference (between the left and right spectrum skirt) suggest that smaller scale turbulence (<500 m) is principally responsible for spectrum broadness.

Abstract

Doppler spectra of a tornado were collected with a radar having a large unambiguous velocity range, ±91 m s−1. Thus for the first time a presentation of nonaliased spectra was possible, showing direct measurement of radial velocities. By fitting the tornado model spectrum to data, the radius of maximum winds and tornado center location are deduced. Tornado spectral signature is defined as a double peak, symmetric with respect to the mean wind spectrum. Histograms of maximum measured wind speeds (from spectrum skirts) for two tornadic storms are obtained, and the histograms of velocity difference (between the left and right spectrum skirt) suggest that smaller scale turbulence (<500 m) is principally responsible for spectrum broadness.

Save