Extreme Precipitation: An Application Modeling N-Year Return Levels at the Station Level

Presented by: Elizabeth Shamseldin; University of North Carolina at Chapel Hill

Joint work with Richard L. Smith; University of North Carolina at Chapel Hill; Stephan Sain, Doug Nychka, and Dan Cooley; National Center for Atmospheric Research

The question under investigation is whether regional climate model return level estimations can be used to obtain return level predictions at the station level. To begin, the relationships of both Community Climate System Model and NCEP grid cell data to the n-year return levels at point locations are explored. The tail of the Generalized Extreme Value distribution (GEV) is fit to the grid cell data above a given threshold. This is similar to the Peaks Over Threshold method. However, here the method used for parameter estimation is a Point Process approach, which leads directly to the GEV parameters. Different threshold values are tested for model stability. The parameter estimates are used to generate n-year return levels. The n-year returns at the point (station) locations are estimated the same way. Various models are considered to predict point location n-year return from grid cell n-year return. Spatial effects are explored. Current results are presented. Future work includes plans to test grid-point models on Regional Climate Model data, as well as investigation of seasonal effects in the model.