Dual-polarization, mobile, X-band, Doppler radar observations of hook echoes in supercells

Since 1993, the University of Massachusetts Microwave Remote Sensing Laboratory and University of Oklahoma School of Meteorology have collaborated in the study of severe storms and tornadoes conducting field experiments with mobile radars (Bluestein and Pazmany, 2000). One of the radar systems is a 9.4 GHz polarimetric Doppler radar, developed to provide storm-scale observations complementing existing very high resolution, but limited range, W-band observations. In addition to providing real-time surveillance of reflectivity, the X-Band radar can record time series data from which co-polarized reflectivity for H and V polarization (Zhh and Zvv), differential reflectivity (Zdr), specific differential phase shift (Kdp), cross-correlation coefficient (ρhv), and Doppler velocity are estimated to 30 km in range.

This paper documents close range, high resolution reflectivity, Doppler velocity, differential reflectivity, and cross-correlation observations of hook echoes in tornadic supercells obtained on 12 May 2004. A variety of fine scale features are observed, including a clear tornado signature in the polarimetric fields. Power-weighted Doppler distributions, analogous to Doppler spectra, are obtained in the vortex area.