Analysis of C-band Dual-polarization Radar Data of a Hailstorm in Northern Guizhou
In order to further explore the local application of C-band dual-polarization radar parameter indicators,this paper analyzes the causes and the dual-polarization radar echo characteristics of a hailstorm that occurred in northern Guizhou on March 16,2022,by using Xishui C-band dual-polarization radar data,ground-based automatic station data,and sounding data.The results show that:(1)This severe convective weather occurred in front of the 500 hPa forward trough,southeast of the low-level low vortex shear,north of the low-and mid-level jet streams and within the ground low-pressure inversion trough.At the same time,the afternoon warming and the intrusion of the mid-upper level dry and cold advection made the stratification more inclined to be unstable,that is,dry and cold in the upper level and warm and humid in the lower level.Moreover,the ground convergence line at the front of the cold front provided the triggering mechanism for the hail process.(2)This hail process was triggered by a multi-cell storm with a maximum reflectivity factor reaching 65 dBz and three-body scattering out of the 40 mm hailstones.There were overhanging structures and bounded weak echo zones in the cross-sections,and convergence velocity pairs were observed in the lower layers.(3)The comparison of the double polarization parameters of 30 mm and 40 mm hailstones suggest that the ZDR of hailstones above the melting layer is in the range of-1 to 0.2 dB,the CC value is between 0.90 and 0.99,and the KDP is 0.From the polarization parameters below the melting layer,the CC values of the 30 mm and 40 mm hailstones are in the range of 0.70-0.90 and 0.80-0.97 respectively,and the ZDR also has increased significantly reaching 0-4 dB.KDP is between 0 and 3.1°·km-1 due to the mixing of large raindrops below the melting layer.(4)The polarization parameters of large hailstones show obvious ZDR columns and KDP columns.For CC valleys,obvious non-uniform beam filled in the CC diagrams,thus obvious three-body scattering in the ZDR and CC diagrams appears.In summary,this paper is only a rough analysis of a multi-cell convective weather process,and the characteristics of the polarization parameters need to be further discussed.In the future,more cases need to be analyzed to improve the standards of various polarization parameters of the C-band dual-polarization weather radar in the severe convective weather and to provide a more accurate reference for the actual operation.
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