The National Center for Atmospheric Research S-band Dual Polarization Doppler Radar (S-POL) detected signatures consistent with the presence of a strong downdraft. An analysis has been made of the hydrometeor types within the downdraft column.
S-POL signatures of high horizontal reflectivity factor (ZH) and low differential reflectivity (ZDR) near ground level suggests the presence of hail, which is statistically an isotropic scatterer. In addition, the large specific differential phase (KDP) suggests the presence of non-spherical scatterers. When considered with high ZH, large KDP suggests the presence of large raindrops. Further, the decrease in the correlation coefficient (ρHV) toward the ground indicates and increasing mixture of hydrometeor types, suggesting hail was melting as it fell toward the ground within the downdraft column.
Supplementary URL: http://www.nssl.noaa.gov/~kscharf/sls02/