Estimation of Big Thompson Flood Rainfall Using Infrared Satellite Imagery.

摘要

During the evening hours of 31 July, 1976, heavy precipitation fell along the Colorado Front Range, resulting in flash flooding in the Big Thompson Canyon, causing the death of 139 people with 35.5 million dollar damage. This report utilizes GOES-1 infrared (IR) imagery to estimate the heavy convective precipitation during the Big Thompson Flood. Analysis of the IR imagery prior to the Big Thompson storm showed that the thunderstorm complex formed at the intersection of frontal and orographic convective lines. A technique is developed to overlay the drainage basins onto the satellite imagery using the All Digital Video Imaging System for Atmospheric Research (ADVISAR) which included corrections due to the satellite sensing cloud tops. The Scofield-Oliver satellite-derived precipitation estimation scheme was modified to reduce the precipitating portion of the cloud to 15 percent of the cloud defined by the 242 K isotherm. IR imagery alone was used to identify overshooting domes which correlated well with areas of heavy precipitation. The computed area averaged precipitation for the Big Thompson Basin was 9.6 percent less than ground truth. Digital-video manipulation on the ADVISAR can indicate areas of heavy precipitation for IR satellite data on a real time basis. (Author)