Initial Validation of a New OSSE Capability

A new Nature Run (NR), called the G5NR, produced by the NASA Global Modeling and Assimilation Office (GMAO), allows for observing system simulations with 7-km horizontal resolution on a global scale. This presentation will present two forms of NR validation for the purposes of Observing System Simulation Experiments (OSSEs). The first validation will look at transitioning from an Observing System Experiment (OSE) to an OSSE at the beginning of the NR period. If the OSSE system is consistent with the real world, the results should show a smooth transition from real-world to simulated-world in terms of analysis and forecast RMS errors for the first two weeks of the NR period. By assimilating only conventional observations at first and then adding various radiance observation instruments in both the OSE and OSSE setting, the instrument impacts seen in the real-world should be mirrored in the simulated-world. The second validation will estimate how quickly a forecast model used in the OSSE system loses predictability with perfect initial condition provided by a NR. This validates this forecast model's capability of simulating “nature.” Results using the Global Forecast System (GFS) in the T574L64 configuration that was operational at NCEP beginning 12 UTC 28 Jul 2010 will be presented. For the purpose of OSSEs, the skill of GFS at forecasting the G5NR should be similar to the skill of GFS at forecasting in operations.