WXlog/20130618 Tornado


A tornado crossed the eastern portion of the Denver International Airport (KDEN) runway complex during the afternoon of 18 June 2013. The CSU-CHILL radar was collecting dual wavelength (S-band / 11 cm and X-band / 3 cm) data in a series of PPI sector scans during the tornado. The following PPI images show reflectivity, radial velocity, and H-V correlation coefficient data at both wavelengths. The azimuthal resolution is higher at X band due to the narrower main beam pattern at the shorter wavelength. (The CHILL dual offset antenna develops 3 dB main beamwidths of ~1 deg at S-band and ~0.33 deg at X-band). Also, the X-band range gate length is 90 m; the S-band gate length is 150 m. One contribution to the generally lower correlation levels at X-band vs. S-band in the higher reflectivity areas may be greater Mie resonance effects at the shorter wavelength. In all of the PPI images, the runways at KDEN and KFTG (Front Range) airports are shown. The two visible range rings are 60 and 70 km.