A 2-km Basin-Scale Nature Run for a Hurricane Regional OSSE System

The applicability of Observing System Simulation Experiments (OSSEs) is influenced by how realistic the underlying Nature Run is. In this work, we describe a basin scale nature run generated for a next generation hurricane OSSE system. This nature run consists of a single 2 km domain covering the entire North Atlantic basin. The single domain configuration addresses the complexity faced when simulating observations on multiscale domains and makes it possible to examine multiple tropical cyclones. NASA's 7km GEOS-5 global nature run is used for initial and boundary conditions. Output data from the basin scale nature run are produced at 30 minute intervals for the entire 17-day forecast and at 5 minute intervals for a 12 hour period during which a hurricane is intensifying. To evaluate the realism of the nature run, an in-depth, storm-centric evaluation of a hurricane originating in the southern Gulf of Mexico and making landfall along the Alabama/Florida Gulf coast is performed. Preliminary evaluations indicate that the storm evolves in a realistic manner.