Evaluation of a Basin-Scale Nature Run for Hurricane OSSEs

The need to improve tropical cyclone forecasts has prompted an interest in performing Observing System Simulation Experiments (OSSEs) to determine the potential impact of proposed observing systems on forecast skill. To this end, the Hurricane Research Division OSSE team has recently completed a 2 km basin scale nature run. This talk discusses the motivation for this nature run and its configuration, which replaces the current nature run as part of the next generation hurricane OSSE system. As this is a nature run for hurricane OSSEs, a storm-focused validation process was necessary to ensure the storm being used for the OSSEs is realistic. The tropical cyclone of interest originates in the southern Gulf of Mexico in NASA’s GEOS-5 nature run, which is the basis for the basin scale nature run. The ongoing evaluation suggests that this particular storm develops realistically and the nature run will lead to realistic OSSEs. Though the validation process particularly focuses on this hurricane, tropical cyclones elsewhere in the numerical simulation will be considered.