Observing System Simulation Experiments for Hurricanes

Abstract:

Observing System Simulation Experiments (OSSEs), when done correctly, provide an effective means to evaluate the potential impact of a proposed observing system, as well as to determine tradeoffs in their design, and to evaluate data assimilation methodology. Great care must be taken to ensure the realism of the OSSEs and in the interpretation of OSSE results. While early OSSEs focused on large-scale numerical weather prediction, more recent OSSEs have included evaluation of the impact of proposed observing systems on smaller-scale phenomena. These have included global OSSEs to evaluate impact on hurricane track forecasting and regional OSSEs aimed at evaluating both track and intensity prediction. Two global OSSEs conducted using the fvGCM nature runs showed a substantial impact of space-based lidar wind profiles on hurricane track predictions. Current OSSEs are using multiple nature runs in which the WRF model, at very high resolution, is embedded within a global T511 nature run that had been generated by ECMWF. These OSSEs are evaluating the potential impact of new (proposed) observing systems on hurricane track and intensity prediction and trade-offs in the design and configuration of these observing systems They are also being used to optimize sampling strategies for current and future airborne and spaceborne observing systems and to evaluate and improve data assimilation and vortex initialization methodology for hurricane prediction. Results from recent OSSEs show the relative impact of alternative lidar technologies and the relative impact of global and regional assimilation on hurricane track and intensity prediction. OSSEs are currently underway to evaluate advanced concepts for hyperspectral infrared (IR) sounding from both polar and geostationary orbit, as well as to evaluate a variety of aspects of hurricane predictability.