Research on dual-polarimetric radar K_DP foot and Z_DR arc recognition and application

Differential reflectivity (Z_DR) arc is known as an arc-shaped region of high differential reflectivity along the inflow edge of the forward flank, while a down shear elongated K_DP maximum near the echo centerline of the storm is known as K_DP foot. The Z_DR arc and the clear horizontal separation between the areas of Z_DR arc and K_DP foot have been confirmed to be the signatures of hydrometeor size sorting within their forward flank regions in supercell storms. Recent studies have indicated that Z_DR arc and Z_DR arc-K_DP foot separation signatures insupercell storms may be related to environmental storm-relative helicity and low-level shear. Based on the conception model and machine learning, the recognition algorithm for K_DP foot and Z_DR arc is designed, and the separation and angle of Z_DR arc and K_DP foot are then calculated. The recognition effect and quantitative calculation are examined using S band polarimetric radar and auto weather station observations of four supercell storms occurred in East China. The results show that the recognition method introduced in this study can identity Z_DR arc and K_DP foot correctly, the variation of Z_DR arc-K_DP foot centroid distance and separation angle can indicate the occurrence of extreme gust.