Exploring the Value of High-Frequency Modeled Precipitation Data

The NOAA Atlas 14 has long been considered the definitive resource to quantify probabilistic risks associated with extreme rainfall for infrastructure and engineering design. These risks are graphically characterized in intensity-duration-frequency (IDF) curves that indicate the probabilistic occurrence that a measured amount of precipitation could occur over a period and at a given location based on its historical observation record. Although jurisdictional planning units often are instructed to build to a 25-year, 24-hour storm, the IDF curves are produced for return periods out to 1000 years and durations ranging from 5 minutes to 60 days. Data that are not directly supported by the observational records (such as sub-hourly data and very long return periods) are imputed from statistical distributions that have been fitted to observational data.

The current work explores using dynamical downscaling to produce climate projections with a finer temporal granularity, including hourly and 5-minute increments. As the Atlas 14 is being updated to Atlas 15, the new Volume 2 will be developed to consider climate change. In some methodologies, projected changes to precipitation IDF curves use statistical functions for sub-daily data when only daily projections are available. This presentation will investigate value added from sub-hourly modeled precipitation data. In this work, 12-km dynamically downscaled simulations will be shown for selected U.S. locations, with a focus on finer temporal increments of data.