We analyze daily extremes of precipitation produced by a six-member ensemble of Pan-Arctic Weather Research and Forecasting that simulated 19 years on the Coordinated Regional Downscaling Experiment Arctic domain. Analysis focuses on four North American regions defined using climatological records, regional weather patterns, and geographical/topographical features. We compare simulated extremes for the winter season with those occurring at corresponding observing stations in the U.S. National Climate Data Center's Global Summary of the Day. We define winter as the 3 month period leading up to and including the climatological sea ice maximum: January-February-March (JFM). Our analysis focuses on winter variations in features of extremes such as magnitudes, spatial scales, and temporal regimes. Using composites of extreme events, we also analyze the processes producing winter season extremes. We compare circulation, pressure, temperature, and humidity fields from the ERA-Interim reanalysis and the model output. Although the model produces lower amounts of extreme precipitation compared to observation, the model is simulating the physical forcing that is found during observed extreme events. Specifically, the model and reanalysis highlight the importance of low-level moisture advection and its interaction with topography. The analysis establishes the physical credibility of the simulations for extreme precipitation events in JFM and their associated atmospheric circulations, laying a foundation for examining projected changes in extreme precipitation.
Available at: http://works.bepress.com/william-gutowski/22/