1 A dual-polarization radar hydrometeor classification algorithm for ...

512513514515516517518519520521522523524525526527528529530531532533534ground according to surface observations. Aggregation is most likely occurring near the Z hgradient below the DGZ, but K dp and Z dr are still high enough to warrant dendrite classificationinstead of aggregates until just above the radar bright band according to the MBFs.c) 07-08 Feb 2012 Great Plains snowstormThe sole case study of plate-like crystals available to us was provided by personalidentification of “hexagonal plates” at the surface within range of the Wichita, KS WSR-88DPradar (c/o , Tyler Dewvall, Accuweather Enterprise Solutions, Inc.). Fig. 12 shows a verticalcross section into the region classified as plates, which appear to fall toward the surface.Extremely high Z dr values ~6.7 dB were observed while K dp < 0.25° km -1 , which matches platescattering simulations of K dp but exceeds the simulated Z dr value by 1.5 dB. The algorithmclassified dendrites until Z dr increased beyond the range expected for dendrites (Table 5). Z drshould increase as crystals attain higher densities or grow more solid than branched. It isimpossible to say whether the dendrite classifications in Fig. 12 were small plates or smalldendrites since we lack in-situ reports and the two are indistinguishable according to ourscattering simulations when diameters are small. Wichita sounding temperature ranges aresuitable for plate growth at these heights.d) 03 Feb 2012 Colorado snowstormTo demonstrate algorithm performance at various wavelengths, simultaneous, dualwavelengthobservations of a Colorado snowstorm were analyzed with the CSU-CHILL radar.When the dendritic growth zone signature was most established within range of both wavelengthsystems, the S-band RHI (Fig. 13) showed K dp ~ 0.6° km -1 while the X-band RHI (Fig. 14)exhibited values correspondingly 3.7 times greater near 2.2° km -1 . Maximum Z dr is between 2.5-3.0 dB. Aggregates are identified surrounding the DGZ where both K dp and Z dr decrease toward24