The future National POES System (NPOESS) is scheduled to be launched during the2008-2018 period. The forecast impact of these future instruments must be assessed withexperiments using simulated observations. These experiments are known as Observing System Simulation Experiments(OSSE). OSSE will provide a guideline for selection and design of the instrument.

This project is a collaboration among several organizations. Data assimilation is performed mainly by a technology-neutral organization such as the National Centers for Environmental Prediction (NCEP). Simpson Weather Associates (SWA) has simulated Doppler Wind Lidar (DWL) observations, and the National Environmental Satellite, Data and Information Service (NESDIS) simulated TOVS level 1B and atmospheric infrared sounder (AIRS) data.

The first "nature run" (true atmosphere for the OSSEs) was provided by the European Centre for Medium- Range Weather Forecasts (ECMWF) for February 1993. The representativeness of the nature run was evaluated and found to be suitable to conduct OSSEs after some adjustment for low level cloud. 

Data impact of existing instruments in real and simulated data are compared for calibration. The impact test showed satisfactory similarity of TOVS 1B data and RAOB wind and surface data between real and simulated analysis. The data impact will be sensitive to systematic errors. Systematic error was added based on analysis increment of real data assimilation.

For DWL OSSE, the bracketing OSSEs are being performed for various concepts to bound the technology-neutral potential impact. Scanning: wavelength; data sampling strategies: various error characterizations are tested through the bracketing OSSE. The results show that scanning is most important, particularly in upper atmosphere. Penetration is important in lower troposphere. Impact are most significant in smaller scale, Compared to lower troposphere data, upper troposperif data show more impact. The data impact in large scale is most sensitive to systematic error added to the data.

The first set of AIRS data has been simulated and is being evaluated. The simulation of cloud motion vectors is under preparation. DWL needs to be assessed with these new simulated data.

Through OSSEs at NCEP, the operational data assimilation systems will be ready to handle new data in time for the launch. This process involves the evaluation of the operational load, the development of the data base and data-processing, and a quality control system. All of this development will accelerate the operational use of data from the future instruments.