A First Look at the DSD Measurements During the UPLIGHTS Project

Abstract:

During the summer 2014, the Upward Lightning Triggering Study (UPLIGHTS) project in Rapid City, SD, recorded several upward lightning events triggered from communication towers with heights from 91 to 191 m above the ground. Two Parsivel disdrometers were used to collect raindrop sizes during the storm events: one instrument is collocated with one of the towers, while the second is placed about 1 mile to the East of the towers. Direct measurements of rain DSDs were taken between June 1 and September 30, 2014.

The goal of this study is to identify significant temporal variations of the estimated DSDs gamma parameters and rainfall rates before and after the lightning flash when using disdrometer data. The modified maximum likelihood (ML) method developed at SDSM&T is applied to determine such parameters of the fitted gamma functions. A previous study (Moore et al, 1964) reported “the gush of rain at the ground” following cloud-to-ground lightning discharge nearby based on radar and raingauge observations. During the summer 2014, we collected not only the radar observations and lightning data, but also the disdrometer and raingauge readings. Preliminary results of these findings are presented.