James Klinman

Date of Award

December 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Atmospheric Sciences

First Advisor

David Delene

Abstract

Reliable in situ measurements are essential for accurately forecasting and nowcasting hailstorms, as they provide insight into storm processes, improve predictions that protect public safety, and help assess potential damage to agriculture and infrastructure. This study evaluates the reliability of in situ hail measurements from the T-28 aircraft’s Hail Spectrometer and assesses their feasibility for radar reflectivity validation and parameterization. Data from 14 flights across five field campaigns were analyzed, focusing on comparisons between one-dimensional (1D) 1-Hz accumulated particle counts and two-dimensional (2D) particle images produced by the Hail Spectrometer. The 2D data were processed using the System for Optical Array Probe Data Analysis Version 2 (SODA2) to enable dataset-wide comparison with the 1D measurements. Consistent discrepancies were found between the 1D and 2D particle size distributions, with the 1D data showing larger maximum particle sizes and lower concentrations of small particles. Manual inspection indicated that the 1D sizing method overestimates particle sizes, potentially due to noise and coincidence effects. Reflectivity estimates derived from both datasets also showed substantial differences, with the 1D data producing significantly higher reflectivity values than both the 2D data and observed reflectivity. The findings highlight the importance of data quality assessment in historical hail measurements and offer new guidance for using this legacy dataset in radar validation and hail modeling efforts.

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