Comparisons of hail kinetic energy derived from radar reflectivity with crop damage reports over the eastern Free State

Abstract

Hail kinetic energy (HKE) derived from radar reflectivity is used to identify hail on the ground over the eastern Free State. The location of crop damage reports is used for validation. Three case studies on days with the highest crop damage claims are analysed. HKE corresponds well with hail on the ground under moist atmospheric convective development, but failed to detect hail under dry atmospheric convective development. The duration and intensity of hail events above farms are also analysed. Several reflectivity threshold levels for hail identification were investigated. A threshold between 45 dBZ and 50 dBZ with a scaling factor resulted in the best correlation between HKE and crop damage location, while a reflectivity cut-off at 50 dBZ or 55 dBZ underestimated hail occurrence.

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