First Comparisons of Rainfall Rates Derived from Radar Differential Reflectivity And Disdrometer Measurements

A comparison between radar-derived rainfall rates and those obtained from a ground-based disdrometer located at the radar site is presented. The radar measurements were made in the vicinity of Chicago, IL, on August 2, 1978, with the CHILL radar of the Illinois State Water Survey. Three radar-derived profiles of rainfall rate versus distance from the radar were obtained for a single storm in the direction of the storm path toward the radar. These profiles indicated the storm motion and the variability of rainfall as the storm progressed toward the radar. The last two profiles support the hypothesis that the storm was in steady state as it passed over the radar site. This provided an opportunity to compare the radar-derived rates with an apparent rate versus distance profile derived from a disdrometer time record of rainfall rate obtained at the radar site. Excellent agreement between the radar and disdrometer measurements of rainfall resulted.