The Kinetic Energy of Hailfalls. Part IV: Patterns of Hailpad and Radar Data

Abstract

Ground-and radar-measured patterns of hail kinetic energy from eight hailstorms have been compared. The radar patterns were shifted horizontally in such a way that the correlation coefficient between the ground and radar data reaches a maximum. The correlation coefficients increased from .7 (no shift) to .9 (optimal shift) on average. The “optimal” shift vector is in good agreement with conceptual models about the kinematics of the storms. The influence of microphysical effects and of the storm dynamics on the agreement between the hailpad-and radar-measured quantities is discussed in detail. The melting of hailstones and the shape of hailstone spectra have been considered in additional analyses, and the impact of these effects on the ground and radar measurements could be isolated. The results imply that the melting of hailstones is more pronounced in supercell storms than in single-cell storms or in multicell storms.