Tropical cyclone precipitation risk in the Southern United States

Abstract

This thesis works to evaluate the new rainfall algorithm that is used to simulate longterm tropical cyclone precipitation (TCP) climatology throughout the southeastern United States. The TCP climatology is based on a fleet of synthetic tropical cyclones developed using National Center for Atmospheric Research/National Centers for Environmental Prediction reanalysis data from 1980 to 2010 and the Coupled Hurricane Intensity Prediction System (CHIPS) model. The climatology is compared to hourly rainfall estimates from the WSR-88D Next Generation Weather Radar (NEXRAD-II) system. In general the synthetic TCP estimates show good agreement with radar-based observations. The rainfall algorithm appears to perform better at coastal locations versus inland ones, and in general has better agreement in the eastern locations considered in this study. In addition, the spatial dependence of radar rainfall estimates was addressed, and in general more extreme TCP-events exhibited a greater degree of event total precipitation variation at grid box-scale. Finally, preliminary work incorporating streamflow measurements as a metric for assessing TCP risk using the synthetic rainfall climatology was begun. Correlation between both grid box-specific and basin-average radar-based event TCP and surface streamflow measurements (from the U.S. Geological Survey National Water Information System) varied greatly, and was generally moderate, and future work should incorporate more thorough streamflow modeling in order to evaluate these comparisons.